EP4736444A1

EP4736444A1 - Metadata for signaling source picture timing information

Info

Publication number: EP4736444A1
Application number: EP24742363.5A
Authority: EP
Inventors: Sean Thomas MCCARTHY; Peng Yin; Gary J. Sullivan
Original assignee: Dolby Laboratories Licensing Corp
Current assignee: Dolby Laboratories Licensing Corp
Priority date: 2023-06-29
Filing date: 2024-06-17
Publication date: 2026-05-06
Also published as: KR20260028121A; WO2025006241A1; CN121444448A

Abstract

Methods, systems, and bitstream syntax are described for video coding and decoding using source picture timing information which is captured by an encoder and is signaled as metadata to a decoder to assist in decoding. The proposed methods include example syntax for signaling source picture timing metadata as supplemental enhancement information (SEI) messaging for both single-layer and multi-layer video sequences.

Description

METADATA FOR SIGNALING SOURCE PICTURE TIMING INFORMATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of priority from U.S. Provisional Patent application Ser. No. 63/511,150, filed on Jun 29, 2023, and U.S. Provisional Patent application Ser. No 63/587,233, filed on 2 October 2023, each of which is incorporated by reference herein in its entirety.

TECHNOLOGY

[0002] The present document relates generally to images and video coding and decoding. More particularly, embodiments of the present invention relate to metadata for signaling source picture timing information.

BACKGROUND

[0003] In 2020, the MPEG group in the International Standardization Organization (ISO), jointly with the International Telecommunications Union (ITU), released the first version of the Versatile Video Coding Standard (VVC), also known as H.266 (Ref. [1]). More recently, the same group has been working on the development of the next generation coding standard that provides improved coding performance over existing video coding technologies. As part of this investigation, new coding techniques are also examined.

[0004] In many applications, given a sequence of decoded pictures, it is of interest to determine the actual temporal distance between corresponding source pictures prior to encoding. For example, for camera-captured content, the temporal distance between source pictures is the difference between the time at which an image sensor was exposed to produce a source picture associated with the current decoded picture and the time at which the image sensor was exposed to produce the source picture associated with a previous decoded picture in output order.

[0005] As appreciated by the inventors here, improved techniques for signaling such source picture timing information (SPTI) are needed and are presented herein.

[0006] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] An embodiment of the present invention is illustrated by way of example, and not in way by limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

[0008] FIGs. 1A through IE depict example scenarios in which the output timing of decoded pictures is different from the timing with which source pictures were captured or otherwise created, thus in need of source picture timing information (SPTI); and

[0009] FIGs. 2A through 2C depict example encoding and decoding processes using SPTI messaging according to embodiments of this invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[00010] Example embodiments that relate to signaling source picture timing information in video coding are described herein. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments of present invention. It will be apparent, however, that the various embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are not described in exhaustive detail, in order to avoid unnecessarily occluding, obscuring, or obfuscating embodiments of the present invention.

SUMMARY

Example embodiments described herein relate to signaling source picture timing information in image and video coding which is captured by an encoder and is signaled as metadata to a decoder to assist in decoding. The proposed methods include example syntax for signaling source picture timing metadata as supplemental enhancement information (SEI) messaging for both single-layer and multi-layer video sequences. SOURCE PICTURE TIMING INFORMATION (SPTI)

INTRODUCTION

[00011] Refs. [2-3] represent earlier proposals to provide some sort of picture timing information via supplemental enhancement information (SEI) messaging. In both contributions, the proposed SEI message was intended to indicate the actual motion speed of the content at capture time for the case in which the video bitstream contains slow motion scenes. Both contributions failed to indicate or signal the timing scale factor between the actual capture timing and the output timing. The proposed messaging could also interfere with conformance issues in a hypothetical reference decoder (HRD).

[00012] Embodiments of the proposed SPTI signaling presented herein intend to address a similar but broader range of use cases as Refs [2-3], whilst avoiding all HRD conformance issues. Example embodiments of SPTI SEI messaging convey information only about when source pictures were captured or otherwise created. The proposed messaging does not influence timing of decoded output pictures and thus does not impact HRD conformance.

[00013] While embodiments are presented herein using example coding syntax of SEI messaging as used in MPEG video coding (such as AVC, HEVC, VVC, and the like), the same information may be transmitted using alternative metadata structures, as used by other coding standards, like AVI and AVS3, and/or future versions of video coding standards.

Example scenarios where source and decoded output picture timing differ

[00014] FIGs 1A through IE illustrate scenarios in which the output timing of decoded pictures is different from the timing with which source pictures were captured or otherwise created. A receiver or post-decode process would not be able to retrieve the original source picture timing from the timing of the output pictures; however, such information could be conveyed within the same bitstream as the coded video by the proposed SPTI SEI message. [00015] FIG. 1A illustrates a typical slow motion playback scenario. The temporal distance between decoded output pictures corresponding to the original source pictures (gray bars) is increased relative to the temporal distance between the original source pictures. In slow motion processing, additional pictures (white bars) are typically synthesized (often using frame interpolation methods) and are inserted prior to encoding to produce smoother motion. When decoded output pictures correspond to both original source pictures and synthesized pictures, it can be beneficial to have a means of indicating which pictures correspond to the original source pictures and which correspond to synthesized pictures, preferably, in addition to providing a means of indicating source picture timing.

[00016] FIG. IB illustrates an example of frame rate conversion in which the temporal distance between decoded output pictures corresponding to original source pictures (gray bars) is the same as the temporal distance between original source pictures. Additional pictures are synthesized (white bars) prior to encoding to increase the output picture rate. For example, Refs. [4-5] describe examples of frame rate conversion using generative neural networks; however, traditional techniques known in the art, say, based on motion-based frame interpolation, could also be applied.

[00017] FIG. 1C illustrates a special case of slow-motion output for high-speed imaging. Some production high-speed cameras currently advertise 9,600 fps at 2,560x1,664 resolution for use in scientific, industrial, automotive, and media applications (e.g., Ref.[6]). FIG. 1C illustrates encoding of high-speed source content such that the timing of decoded output pictures corresponds to standard frame rates to facilitate human inspection whilst information contained in an SPTI SEI message could be used to facilitate scientific and machine analysis.

[00018] FIG. ID illustrates encoding of time-lapse source content such that the timing of decoded output pictures corresponds to standard frame rates to facilitate human viewing and inspection, whilst information contained in an SPTI SEI message could be used to facilitate scientific and machine analysis.

[00019] FIG. IE illustrates a “rewind” use case in which decoded pictures are output in reverse order relative to the corresponding source pictures. For example, temporal reversal of source video is used in media applications for artistic effect and storytelling. Source picture timing information contained in an SPTI SEI message could be used to facilitate causal playback and facilitate scientific and machine analysis.

[00020] FIG. 2A depicts an example encoding and decoding process using SPTI messaging. As depicted in FIG. 2A, given source input generated by video source (105), in an encoder, source picture timing information (109) is captured and encoded by SPTI message encoder (115) as SPTI messaging (e.g., SEI messaging) (117). Source content (107) may be camera-captured content, screen-captured content, content generated using artificial intelligence (Al) technologies, or generated by any other means. After compression (110), such messaging (117) is multiplexed with the coded bitstream and is transmitted downstream. Such multiplexing may be as part of header information in the bitstream or as part of supplementary metadata (e.g., SEI messaging, video usability information (VUI), and the like). In a decoder, the received bitstream is separated as an SPTI signal (124) and video decoded frames (122) generated from video decoder (120), matching to the video encoder (110). Then, playback devices (130, 135) can generate output video at either the HRD-defined timing (137) or/and at the source timing (132). For playback using source timing, in an embodiment, the coded pictures may be stored in a buffer (140) connected to the playback system (130) having timing controlled by the source picture timing information, which is extracted from the SPTI message.

[00021] The system illustrated in FIG. 2 A could be used to facilitate playback of high-speed, time-lapse, slow motion, and reverse motion coded video for human viewing on commonly available consumer and professional displays.

[00022] FIG. 2B depicts an example encoding and decoding process using SPTI messaging but targeted for machine analysis. Machine analysis includes conventional and Al-based machine analysis. Encode-side processes are the same as described in the context of FIG. 2A; however, on the decode side, decoded output pictures and source picture timing information extracted from the SPTI message are input to a machine analysis system (140). Examples of machine analysis systems include determination of the speed of a car; determination of cardiac timing in medical imaging; tracking of athletes and balls in sports video; modelling of physics in a scene to facilitate integration in gaming; video-to-text applications; forensic analysis to detect missing or deleted source pictures in a coded video bitstream; and differentiation of original source pictures from synthesized pictures in the coded bitstream.

[00023] FIG. 2C illustrates the use of data conveyed in an SPTI SEI message as auxiliary input to post-decode processes (145) of decoded output pictures (122). Post-decode processes include conventional and Al-based processes, including neural network processes signaled by post-filtering metadata messages. Encode side processes are the same as described in the context of FIG. 2A. On the decode side, decoded output pictures and source picture timing information extracted from the SPTI message decoder (125) are input to a post-decode processor (145). Examples of post-decode processes include frame rate conversion; synthesis of video using generative Al technologies; and motion-aware spatial scaling.

Example SPTI Embodiments

Source picture timing information SEI message

Aspect 1

[00024] Source picture timing information can be conveyed as the temporal distance, denoted as source picture interval, between source pictures that correspond to sequential decoded output pictures. The source picture interval can be determined from the number of time units that pass in one second, indicated by a time scale variable, say, spti_time_scale, and the number of time units corresponding to source picture interval, indicated by spti_num_units_in_source_picture_interval.

The syntax elements spti_time_scale and spti_num_units_in_source_picture_interval can be conveyed alone or in combination with other syntax elements and conditions as described elsewhere in this document. An example of such an SEI message is depicted in Table 1. In some applications, it may be beneficial to constrain the values of spti_time_scale and spti_num_units_in_source_picture_interval to have fixed values within the whole coded sequence.

Table 1. Example 1 of an SPTI SEI message

[00025] The source picture timing information (SPTI) SEI message indicates the temporal distance between source pictures associated with the corresponding decoded output pictures prior to encoding, e.g., for camera-captured content, the temporal distance between source pictures is the difference between the time at which an image sensor was exposed to produce a source picture associated with the current decoded picture and the time at which the image sensor was exposed to produce the source picture associated with a previous decoded picture in output order. spti_time_scale specifies the number of time units that pass in one second. The value of spti_time_scale shall not be equal to 0. For example, a time coordinate system that measures time using a 27 MHz clock has an spti_time_scale of 27,000,000. spti_num_units_in_source_picture_interval specifies the number of time units of a clock operating at the frequency spti_time_scale Hz that corresponds to the indicated source picture interval of corresponding consecutive pictures in output order in the coded layer-wise video sequence (CLVS). The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

The indicated source picture interval, denoted by the variable SourcePicturelnterval, in units of seconds, is equal to the quotient of spti_num_units_in_source_picture_interval divided by spti_time_scale. For example, to represent a source picture interval equal to 0.04 seconds, spti_time_scale may be equal to 27,000,000 and spti_num_units_in_source_picture_interval may be equal to 1,080,000.

When picture n is a picture that is output and is not the first picture of the bitstream that is output, the value of the variable SourcePictureTimef n ] is derived as follows: SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval , (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, then the value of SourcePictureTimef 0 ] is inferred to be 0.

All source picture timing information SEI messages that apply to the same CLVS shall have the same values of syntax elements spti_time_scale and spti_num_units_in_source_picture_interval.

Note: As used herein, the terms equation (xxxl) or Table xxx simply indicate an unknown equation or Table number that may be used in a coding specification document describing this signaling and which may include an unknown number of other equations or Tables preceding this one.

Aspect 2

[00026] As an alternative, syntax elements indicating an elemental source picture interval, spti_num_units_in_elemental_source_picture_interval, and source picture interval scale, spti_source_picture_interval_scale_factor, can be signaled instead of spti_num_units_in_source_picture_interval. This syntax allows to apply multiplication instead of division when calculating the SourcePicturelnterval value. Differences with respect to Aspect 1 are indicated using an Italic font.

Table 2. Example 2 of an SPTI SEI message

Updated Semantics spti_num units_in eZeme/7taZ source_picture_interval specifies the number of time units of a clock operating at the frequency spti_time_scale Hz that corresponds to the indicated elemental source picture interval of consecutive pictures in output order in the CLVS.

The indicated elemental source picture interval, also to be denoted by the variable EZementaZSourcePicturelnterval, in units of seconds, is equal to the quotient of spti_num_units_in_eZementaZ_source_picture_interval divided by spti_time_scale. For example, to represent an elemental source picture interval equal to 0.04 seconds, spti_time_scale may be equal to 27,000,000 and spti_num_units_in_eZementaZ_source_picture_interval may be equal to 1,080,000. spti_source _picture _interval_scale _Jactor specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

When the current picture is the first picture in the CLVS to which an SPTI SEI message applies, the value ofspti_source_picture_interval_scale^factor should be 0. When the current picture is the first picture in the CLVS to which an SPTI SEI message applies and the value of spti_source_picture_interval_scale^factor is greater than 0, it shall not have a huge magnitude ( to avoid having a se(v) code that is too long).

The indicated source picture interval, denoted by the variable SourcePicturelnterval, in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti_source_picture_interval_scale^factor.

When picture n is a picture that is output and is not the first picture of the bitstream that is output, the value of the variable SourcePictureTimef n ] is derived as follows: SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval , (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Note: In some applications, it could be preferred to signal spti_source_picture_interval_scale_factor as a ue(v) instead of se(v) and send a separate flag, spti_source_picture_interval_scale_sign_flag, to indicate that the value of SourcePicturelnterval is less than zero as follows: spti_source _picture_interval_scale _Jactor specifies the absolute magnitude of a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture. The indicated source picture interval, denoted by the variable SourcePicturelnterval, in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti_source_picture_interval_scale^factor. spti_source _picture -interval _sign -flag equal to 0 specifies the sign of the scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS is greater than or equal to zero. spti_source_picture_interval_sign^flag equal to 1 specifies the sign of the scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS is less than zero.

When picture n is a picture that is output and is not the first picture of the bitstream that is output, the value of the variable SourcePictureTimef n ] is derived as follows:

- If spti_source_picture_interval_sign^flag is equal to 0, SourcePictureTimef n ] = SourcePictureTimef previousPidnOutputOrder ] + SourcePicturelnterval

- Otherwise, spti_source_picture_interval_sign^flag is equal to 1, SourcePictureTimef n ] = SourcePictureTimef previousPidnOutputOrder ] - SourcePicturelnterval where previousPidnOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Aspect 3

[00027] Source picture timing information can be indicated for all decoded output pictures for temporal sublayers having Temporalld less than or equal to a specified maximum TemporallD by syntax element spti_sublayer_max_tid. Several SPTI SEI messages could be present for a CLVS to indicate source picture timing information for different values of maximum TemporallD. The variable Temporalld may be specified as in VVC.

Differences with respect to Aspect 2 are indicated in an Italic font.

Table 3. Example 3 of an SPTI SEI message

Updated semantics spti_sublayer_max_tid specifies the maximum temporal sublayers for which the SPTI SEI message applies. spti_source_picture_interval_scale_factor specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having a value of TemporallD less than or equal to spti_sublayer_max_tid. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

The indicated source picture interval, denoted by the variable SourcePicturelnterval, in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti_source_picture_interval_scale_factor.

SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Aspect 4 [00028] As an alternative to Aspect 3, source picture timing information can be indicated for decoded output pictures of specific temporal sublayers by syntax element spti_sublayer_tid. The temporal distance between the source picture corresponding to the first decoded output picture of the temporal base layer (Temporalld equal to 0) and the source picture corresponding to the first decoded output picture of another temporal sublayer (Temporalld greater than 0) can be specified by syntax element spti_sublayer_delay_factor.

[00029] Several SPTI SEI messages could be present for a CLVS to indicate source picture timing information for different values of TemporallD.

Differences with respect to Aspect 2 are indicated in an Italic font.

Table 4. Example 4 of an SPTI SEI message

Updated semantics spti_sublayer_tid specifies the temporal sublayer for which the SPTI SEI message applies. spti_source_picture_interval_scale_factor specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having a value ofTemporallD equal to spti_sublayer_tid. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

The indicated source picture interval, denoted by the variable SourcePicturelnterval, in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti_source_picture_interval_scale_factor. spti_sublayer_source _picture_delay _J actor specifies a scale factor used in determining the temporal distance between the source picture corresponding to the first decoded output picture of temporal sublayer having a value of Temporalld equal to 0 and the source picture corresponding to the first decoded output picture of the temporal sublayer having a value of TemporallD equal to spti_sublayer_tid. When spti_sublayer_tid is equal to 0 the value of spti_sublayer_source_picture_delay^factor shall be 0.

The indicated sublayer source picture delay, denoted by the variable SublayerSourcePictureDelay, in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti_sublayer_source_picture_delciy ^factor.

When picture n is a picture that is output and corresponds to the temporal sublayer indicated by spti_sublayer_tid and is not the first picture of the bitstream that is output, the value of the variable SourcePictureTimef n ] is derived as follows:

SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval + SublayerSourcePictureDelay (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Aspect 5

[00030] Source picture timing information can be indicated for several temporal sublayers by looping on the value of syntax element spti_max_sublayers_minus 1.

Differences with respect to Aspect 3 are shown in an Italic font.

Table 5. Example 5 of an SPTI SEI message

Updated semantics spti_max sublayers _minus_l plus 1 specifies the maximum number of temporal sublayers that may be present in the CLVS. spti_suWayer_source_picture_interval_scale_factor i ] specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having Temporalld less than or equal to i. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

The indicated source picture interval associated with output pictures having Temporalld less than or equal to i, denoted by the variable Source Picture Interval/ i ], in units of seconds, is equal to the product of ElementalSourcePicturelnterval and spti source pictLire interval scale factor/ i ].

When picture n is a picture that is output having Temporalld less than or equal to i and is not the first picture of the bitstream that is output, the value of the variable SourcePictureTimef n ] is derived as follows:

SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] +

Sou rcePi ct Lire Interval/ i ] (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0. Aspect 6

[00031] Source picture timing information can be indicated as inferred for dyadic temporal sublayer coding structure by the value of syntax element spti_sublayer_dyadic_flag.

Differences with respect to Aspect 5 are indicated in an Italic font.

Table 6. Example 6 of an SPTI SEI message

Updated semantics spti_sublayer_dyadic _Jlag equal to 1 indicates temporal sublayers are coded in a dyadic relatationship and that the spti_source_picture_interval_scale^factor[ i ] syntax element is not present in the SPTI SEI message. ( Ed: may also indicate other syntax elements are also not present). spti_sublayer_dyadic^flag equal to 0 indicates temporal sublayers might not be coded in a dyadic relationship and that the spti_source_picture_interval_scale^factor[ i ] syntax element is present in the SPTI SEI message. ( Ed: may also indicate other syntax elements are also present). spti_sublayer_source_picture_interval_scale_factor[ i ] , when present, specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having Temporalld less than or equal to i. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

The indicated scale factor, denoted by the variable SublayerScaleFactor[ i ], is determined as follows:

- If spti_sublayer_dydadicjlag is equal to 0, Sublay erScaleFactor[ i ] is equal to spti_sublayer_source_picture_interval_scale^factor[ i ].

- Otherwise, spti_sublayer_dydadic^flag is equal to 1, Sublay erScaleFactor[ i ] is equal to 2( spti_max_sublayers_minus_l - i )

The indicated source picture interval associated with output pictures having Temporalld less than or equal to i, denoted by the variable SourcePicturelntervalf i ], in units of seconds, is equal to the product of ElementalSourcePicturelnterval and Sublay erScaleFactor\ i ].

SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelntervalf i ] (xxxl) where previousPicInOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Aspect 7

[00032] Source picture timing information can be indicated as inferred for a specified temporal sublayer coding structure by the value of spti_sublayer_implicit_timing_flag and value of spti_sublayer_implicit_timing_type to indicate the type of temporal sublayer coding structure. Differences with respect to Aspect 5 are indicated in an Italic font. Table 7. Example 7 of an SPTI SEI message

Updated semantics spti sublayer unplicit timing^flag equal to 1 indicates the spti_sublayer_implicit_timing_type syntax element is present in the SPTI SEI message. spti_sublayer_implicit_timing^flag equal to 0 indicates the spti_sublayer_implicit_timing_type syntax element is absent from the SPTI SEI message. spti_sublayer_implicit_timing_type, when present, indicates the temporal sublayer coding structure as described in Table 7axx. When not present, the value of spti_sublayer_implicit_timing_type is inferred to be equal to 0. The value of spti_sublayer_implicit_timing_type shall be in the range of 0 to 2, inclusive, in bit streams conforming to this edition of this document. Values of 3 to 7, inclusive, for spti_sublayer_implicit_timing_type are reserved for future use by ITU-T | ISO/IEC and shall not be present in bit streams conforming to this edition of this document. Decoders conforming to this edition of this document shall ignore SPTI SEI messages with spti_sublayer_implicit_timing_type in the range of 3 to 7, inclusive. Values of spti_sublayer_implicit_timing_type greater than 7 shall not be present in bitstreams conforming to this edition of this document and are not reserved for future use. When spti_sublayer_implicit_timing_type is equal to 2, a field-frame information SEI message shall be present for the current picture.

Table 7 axx - Example informative description of spti_sublayer_implicit_timing_type spti_sublayer_source_picture_interval_scale_factor[ i ] , when present, specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having Temporalld less than or equal to i. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture.

- If spti_sublayer_implicit_timingfilag is equal to 0, Sublay erScaleFactor[ i ] is equal to spti_sublayer_source_picture_interval_scale^factor[ i ].

- Otherwise, if spti_sublayer_implicit_timingfilag is equal to 1 and spti_sublayer_implicit_timing_type is equal to 0, Sublay erScaleFactor[ i ] is equal to 2( spti_max_sublayers_minus_l - i )

- Otherwise, spti_sublayer_implicit_timingfilag is equal to 1 and spti_sublayer_implicit_timing_type is equal to 1, Sublay erScaleFactor[ i ] is equal to ( Ed: TBD and may also be specified by external means) The indicated source picture interval associated with output pictures having Temporalld less than or equal to i, denoted by the variable SourcePicturelntervalf i ], in units of seconds, is equal to the product of ElementalSourcePicturelnterval and Sublay erScaleFactor\ i ].

Aspect 8

[00033] Decoded output pictures associated with a temporal sublayer can be indicated as corresponding to either original source pictures or synthesized pictures (e.g., as in frame rate conversion applications) by the value of spti_synthesized_picture_flag.

Differences with respect to Aspect 5 are indicated in an Italic font.

Table 8. Example 8 of an SPTI SEI message

Updated semantics spti_sublayer_synthesized _picture _ lag equal to 1 indicates that decoded output pictures belonging to the ith temporal sublayer are synthesized and do not correspond to unmodified original source pictures. spti_sublayer_synthesized_picture^flag equal to 0 provides no such indication.

Aspect 9

[00034] The type of relationship between source picture timing and decoded output picture timing can be indicated by spti_source_picture_timing_type.

Differences with respect to Aspect 5 are indicated in an Italic font.

Table 9. Example 9 of an SPTI SEI message

Updated semantics spti_source _picture_timing_type indicates the timing relationship between source pictures and corresponding decoded output pictures as specified in Table 9axx, where

( spti_source_picture_timing_type & bitMask ) not equal to 0 indicates that the timing relationship has the interpretation associated with the bitMask value in Table 9axx. When spti_source_picture_tiniing_type is greater than 0 and ( spti_source_picture_tiniing_type & bitMask ) is equal to 0, the interpretation associated with the bitMask value is not applicable to the SPTI. When spti_source_picture_tiniing_type is equal to 0, the timing relationship may be specified by the application. The value of spti_source_picture_timing_type shall be in the range of 0 to 127, inclusive, in bitstreams conforming to this edition of this document. Values of 128 to 255, inclusive, for spti_source_picture_timing_type are reserved for future use by ITU-T | ISO/IEC and shall not be present in bitstreams conforming to this edition of this document. Decoders conforming to this edition of this document shall ignore SPTI SEI messages with spti_source_picture_timing_type in the range of 128 to 255, inclusive.

Table 9axx - Example definition of spti_source_picture_timing_type

- If ( spti_source_picture_timing_type & bitMask ) is equal to 0, SourcePictureTime[ n ] = SourcePictureTime[ previousPidnOutputOrder ] + SourcePicturelnterval

- Otherwise, ( spti_source_picture_timing_type & bitMask is equal to 1, SourcePictureTime[ n ] = SourcePictureTime[ previousPidnOutputOrder ] - SourcePicturelnterval where previousPidnOutputOrder is the last picture that is output that precedes picture n in output order (if any). When the value of SourcePictureTimef 0 ] is not provided by external means not specified in this document, the value of SourcePictureTimef 0 ] is inferred to be 0.

Aspect 10 [00035] The type of relationship between source picture timing and decoded output picture timing can be affirmatively specified as the same by spti_source_timing_equals_output_timing_flag.

Differences with respect to Aspect 5 are indicated with an Italic font.

Table 10. Example 10 of an SPTI SEI message

Updated semantics spti_source_timing_equals_output_timing_flag equal to 1 indicates the timing of source pictures is the same as the timing of corresponding decoded output pictures. spti_source_timing_equals_output_timing^flag equal to 0 indicates the timing of source pictures might not be the same as the timing of corresponding decoded output pictures.

When spti_source_timing_equals_output_timing^flag is equal to 1 and a picture timing SEI message is present for the current picture, source picture timing could be determined from information conveyed in the picture timing SEI message.

Aspect 11 [00036] Discontinuities in the timing of source pictures such as scene cuts and splices can be indicated by a spti_source_timing_discontinuity_flag or, alternatively, by spti_source_timing_discontinuity_type.

Differences with respect to Aspect 5 are indicated with an Italic font.

Table 11. Example 11 of an SPTI SEI message

Updated semantics spti_source_timing_discontinuity _jlag equal to 1 indicates the timing of source pictures corresponding to decoded output pictures is discontinuous. spti_source_timing_equals_output_timing^flag equal to 0 provides no such indication.

Note: Source picture timing could be discontinuous because of a scene cut, splice, and in event- triggered security video, as examples.

Aspect 12

[00037] Discontinuities in the timing of source pictures such as scene cuts and splices can be indicated by spti_source_timing_discontinuity_type and further defined by the spti_source_timing_discontinuity_type and spti_source_transition_type syntax elements.

Differences with respect to Aspect 11 are indicated with an Italic font. Table 12. Example 12 of an SPTI SEI message

Updated semantics spti_source_timing_discontinuity_type, when present, equal to 1 indicates the timing of source pictures corresponding to decoded output pictures is discontinuous as specified in Table 12axx. When not present, the value ofspti_source_timing_discontinuity_type is inferred to be equal to 0. Table 12axx - Example definition of spti_source_timing_discontinuity_type spti_source_transition_type, when present, indicates the type of scene transition that applies to the source pictures corresponding to decoded output pictures as specified in Table 12bxx, where ( spti_source_transition_type & bitMask ) not equal to 0 indicates that the scene transition relationship has the interpretation associated with the bitMask value in Table 12bxx. When spti_source_transition_type is greater than 0 and ( spti_source_transition_type & bitMask ) is equal to 0, the interpretation associated with the bitMask value is not applicable to the SPTI. When spti_source_transition_type is equal to 0, the scene transition may be specified by the application. When not present, spti_source_transition_type is inferred to be equal to 0.

The value of spti_source_transition_type shall be in the range of 0 to 127, inclusive, in bitstreams conforming to this edition of this document. Values of 128 to 255, inclusive, for spti_source_transition_type are reserved for future use by ITU-T | ISO/IEC and shall not be present in bitstreams conforming to this edition of this document. Decoders conforming to this edition of this document shall ignore SPTI SEI messages with spti_source_transition_type in the range of 128 to 255, inclusive.

Table 12bxx - Example definition of spti_source_transition_type

Considerations for the persistence scope of the SEI message

Option 1 the SEI message persists for the entire CLVS.

Semantics

When a source picture timing information SEI message is present for any picture of a CLVS of a particular layer, a source picture timing information SEI message shall be present for the first picture of the CLVS. The source picture timing information SEI message persists for the current layer in decoding order from the current picture until the end of the CLVS. All source picture timing information SEI messages that apply to the same CLVS shall have the same content.

Option 2 the persistence scope of the SEI message is specified in the syntax of the SEI message.

Semantics spti_cancel_flag equal to 1 indicates that the SPTI SEI message cancels the persistence of any previous SPTI SEI message in output order that applies to the current layer. Spti_cancel_flag equal to 0 indicates that SPTI follows. spti_persistence_flag specifies the persistence of the SPTI SEI message for the current layer. spti_persistence_flag equal to 0 specifies that the SPTI SEI message applies to the current decoded picture only. spti_persistence_flag equal to 1 specifies that the SPTI SEI message applies to the current decoded picture and persists for all subsequent pictures of the current layer in output order until one or more of the following conditions are true: - A new CL VS of the current layer begins.

- The bitstream ends.

- A picture in the current layer in an AU associated with a SPTI SEI message is output that follows the current picture in output order. [00038] In another embodiment, Table 13 depicts another example of a proposed SPTI message.

Table 13. Example 13 of an SPTI SEI message

00039] Compared to previous embodiments, Table 13 includes the following changes. spti_num_units_in_elemental_interval is now unsigned 18-bit instead of 32-bit to save bits. Table 13axx below is an enhanced version of Table 9axx described earlier, adding clarification to the various descriptions, like “slow motion” and the like. Furthermore, new semantic constrains are added to prevent mutually exclusive timing relationships between source pictures and corresponding decoded output pictures. As an example, the semantics prevent the combination of “high-speed imaging” and “time-lapse imaging.” spti_source_timing_equals_output_timing_flag (defined in Aspect 10) is now replaced by the spti_source_timing_info_present_flag. spti_source_timing_info_present_flag (defined in Aspect 9) is now spti_source_type. Flag spti_source_type_present_flag is added and is defined as follows: spti_source_type_present_flag equal to 1 indicates the syntax element spti_source_type is present in the SEI message. spti_source_type_present_flag equal to 0 indicates the syntax element spti_source_type is not present in the SEI message

For completeness, the semantics of the renamed flags are: spti_source_type, when present, indicates the timing relationship between source pictures and corresponding decoded output pictures as specified in Table 13axx below, where

( spti_source_type & bitMask ) not equal to 0 indicates that the timing relationship has the interpretation associated with the bitMask value in the corresponding row of Table 13axx. When spti_source_type is greater than 0 and ( spti_source_type & bitMask ) is equal to 0, the interpretation associated with the bitMask value is not applicable to the SPTI SEI message. When not present, the value of spti_source_picture_type is inferred to be 0. When spti_source_type is equal to 0, the timing relationship may be specified by the application.

The value of spti_source_type shall be in the range of 0 to 127, inclusive, in bitstreams conforming to this edition of this document. Decoders conforming to this edition of this document shall ignore SPTI SEI messages with spti_source_picture_timing_type in the range of 128 to 65535, inclusive.

Table 13axx - Interpretation of spti_source_type

The value of ( spti_source_type & 0x04 ) & ( spti_source_type & 0x08 ) shall be zero (i.e., spti_source_type shall not simultaneously indicate high-speed imaging and time-lapse imaging).

The variable temporalReversalFlag is equal to ( spti_source_type & 0x10 )? 1 : 0.

Alternatively, one may define a variable temporalReversalFactor equal to

( spti_source_type & 0x10 )? -1 : 1 , with a corresponding modification to equation (8-X) as noted below. spti_source_timing_info_present_flag equal to 1 indicates syntax elements spti_time_scale, spti_num_units_in_elemental_interval, spti_max_sublayers_minus_ 1 , spti_sublayer_interval_scale_factor[ i ], and spti_sublayer_synthesized_picture_flag[ i ] are present in the SEI message. spti_source_timing_info_present_flag equal to 0 indicates those syntax elements are not present in the SEI message.

(Note, spti_num_units_in_elemental_interval is a simplified name of spti_num_units_in_elemental_source_picture_interval, defined earlier in Aspect 2) spti_sublayer_interval_scale_factor[ i ], when present, specifies a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order in the CLVS having Temporalld less than or equal to i. The value 0 may be used to indicate that the source picture corresponding to the current decoded output picture is identical to the source picture corresponding to the previous decoded output picture. When ( spti_source_type & 0x04 ) is equal to 1, the value of spti_sublayer_interval_scale_factor[ i ] should be 0.

The indicated source picture interval associated with output pictures having Temporalld less than or equal to i, denoted by the variable SourcePicturelntervalf i ], in units of seconds, is derived as follows:

SourcePicturelntervalf i ] = ElementalSourcePicturelnterval * spti_sublayer_interval_scale_factor[ i ] * ( 1 - 2 * temporalReversalFlag ) (8-X)

(Note: spti_sublayer_interval_scale_factor[i] is a simplified name of spti_sublayer_source_picture_interval_scale_factor[ i ] defined earlier. )

When using the temporalReversalFactor variable, equation (8-X) is modified as:

SourcePicturelntervalf i ] = ElementalSourcePicturelnterval * spti_sublayer_interval_scale_factor[ i ]

* temporalReversalFactor (8-X)

References Each one of the references listed herein is incorporated by reference in its entirety. The term JVET refers to the Joint Video Experts Team of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29.

[1] “Versatile Video Coding,” Rec. ITU-T H.266, August 2020.

[2] H. B. Teo, et al., “AHG9: Alternative Picture Timing SEI”, JVET-AC0141, 29th Meeting, by teleconference, 11-20 January 2023.

[3] H. B. Teo, et al., “AHG9: Alternative Output Timing Hint SEI”, JVET-AD0161, 30th Meeting, Antalya, Turkey, 21-28 April 2023.

[4] B. Chen, et al., “AHG9: Generative Face Video SEI Message,” JVET-AC0088, by teleconference, 11-20 January 2023.

[5] B. Chen, et al., “AHG9: Common SEI Message of Generative Face Video”, JVET-AD0051, 30th Meeting, Antalya, Turkey, 21-28 April 2023.

[6] Phantom/ AMETEK T4040 camera main Web Page, accessed June 24, 2023, https://www.phantomhighspeed.com/products/cameras/tseries/t4040.

EXAMPLE COMPUTER SYSTEM IMPLEMENTATION

[00040] Embodiments of the present invention may be implemented with a computer system, systems configured in electronic circuitry and components, an integrated circuit (IC) device such as a microcontroller, a field programmable gate array (FPGA), or another configurable or programmable logic device (PLD), a discrete time or digital signal processor (DSP), an application specific IC (ASIC), and/or apparatus that includes one or more of such systems, devices or components. The computer and/or IC may perform, control, or execute instructions relating to signaling source picture timing information in image and video coding, such as those described herein. The computer and/or IC may compute any of a variety of parameters or values that relate to signaling source picture timing information in image and video coding described herein. The image and video embodiments may be implemented in hardware, software, firmware and various combinations thereof.

[00041] Certain implementations of the invention comprise computer processors which execute software instructions which cause the processors to perform a method of the invention. For example, one or more processors in a display, an encoder, a set top box, a transcoder, or the like may implement methods related to signaling source picture timing information in image and video coding as described above by executing software instructions in a program memory accessible to the processors. Embodiments of the invention may also be provided in the form of a program product. The program product may comprise any non-transitory and tangible medium which carries a set of computer-readable signals comprising instructions which, when executed by a data processor, cause the data processor to execute a method of the invention. Program products according to the invention may be in any of a wide variety of non-transitory and tangible forms. The program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like. The computer-readable signals on the program product may optionally be compressed or encrypted.

[00042] Where a component (e.g. a software module, processor, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a "means") should be interpreted as including as equivalents of that component any component which performs the function of the described component (e.g., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated example embodiments of the invention.

EQUIVALENTS, EXTENSIONS, ALTERNATIVES AND MISCELLANEOUS

[00043] Example embodiments that relate to signaling source picture timing information in image and video coding are thus described. In the foregoing specification, embodiments of the present invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what is the invention, and what is intended by the applicants to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any definitions expressly set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. [00044] Various aspects of the present disclosure may be appreciated from the following Enumerated Example Embodiments (EEEs):

EEE 1. A method for decoding a video bitstream, the method comprising: receiving a coded video bitstream comprising an encoded picture section including an encoding of a sequence of video pictures and a signaling section including source picture timing parameters, wherein the source picture timing parameters comprise: a source-picture time-scale parameter indicating the number of time units passing in one second; and a source-picture number-of units-in-source-picture interval parameter indicating a number of time units of a clock operating at the frequency of the source-picture time-scale parameter; and decoding the sequence of video pictures based on the source picture timing parameters.

EEE 2. The method of EEE 1, further comprising computing a source-picture-interval (SourcePicturelnterval) value as the quotient of the source-picture number-of units-in sourcepicture interval divided by the source-picture time-scale.

EEE 3. A method for decoding a video bitstream, the method comprising: receiving a coded video bitstream comprising an encoded picture section including an encoding of a sequence of video pictures and a signaling section including source picture timing (SPT) parameters, wherein the source picture timing parameters comprise: a source-picture time-scale parameter indicating the number of time units passing in one second; a source-picture number-of units-in-elemental-source-picture interval parameter indicating a number of time units of a clock operating at the frequency of the source-picture time-scale parameter corresponds to an indicated elemental source picture interval of consecutive output pictures; and a source-picture interval scale factor parameter specifying a scale factor; and decoding the sequence of video pictures based on the source picture timing parameters. EEE 4. The method of EEE 3, further comprising: computing a source-picture-interval (SourcePicturelnterval) value as the multiplication product of an elemental source picture interval with the source-picture interval scale factor, wherein the elemental source picture interval is computed as the quotient of the source-picture number-of units-in-elemental-source- picture interval parameter divided by the source-picture time-scale parameter.

EEE 5. The method of EEE 2 or EEE 4, further comprising computing a source-picture time for picture n as:

SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval, wherein picture n, n > 0, denotes an index of an output picture that is not the first output picture in the video bitstream, and variable previousPicInOutputOrder denotes the last picture that is output that precedes picture n in output order (if any).

EEE 6. The method of EEE 3, wherein the source picture timing parameters further comprise a source picture sublayer maximum temporal ID identifying a maximum sublayer for which the SPT parameters apply.

EEE 7. The method of EEE 3, wherein the source picture timing parameters further comprise: a source picture temporal sublayer ID for which SPT parameters apply; and a source picture sublayer delay factor which specifies a scale factor used in determining a temporal distance between a source picture corresponding to the first decoded output picture of a temporal sublayer having a value of Temporalld equal to 0 and a source picture corresponding to the first decoded output picture of temporal sublayer having a value of TemporallD equal to the source picture temporal sublayer ID.

EEE 8. The method of EEE 7, further comprising computing a source-picture time for picture n as: SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval +SublayerSourcePictureDelay, wherein picture n, n > 0, denotes an index of an output picture that is not the first output picture in the video bitstream and variable previousPicInOutputOrder denotes the last picture that is output that precedes picture n in output order (if any), and Sublayers ourcePictureDelay indicates the source picture sublayer delay factor.

EEE 9. The method of EEE 3, wherein the source-picture interval scale factor parameter is specified for each one of N sublayers, wherein N > 0.

EEE 10. The method of EEE 9, wherein the source picture timing parameters further comprise a source picture sublayer dyadic flag which if set to 1 indicates that temporal sublayers are coded in a dyadic relatationship and that the source-picture interval scale factor parameter specifying a scale factor syntax element is not present.

EEE 11. The method of EEE 9, wherein the source picture timing parameters further include a source picture sublayer implicit timing flag which when set to 1 indicates that sublayer implicit timing type information is present for each of the sublayers.

EEE 12. The method of EEE 9, wherein the source picture timing parameters further include a source picture sublayer synthesized picture flag for each one of the N sublayers, wherein, when set to 1 indicate that decoded output pictures belonging to the i-th temporal sublayer are synthesized and do not correspond to unmodified original source pictures.

EEE 13. The method of EEE 9, wherein the source picture timing parameters further include a source picture timing type parameter which indicates a timing relationship between source pictures and corresponding decoded output pictures according to a mapping table. EEE 14. The method of EEE 9, wherein the source picture timing parameters further include a source picture-timing-equals-output-timing flag, which when set to 1 indicates that timing of source pictures is the same as the timing of corresponding decoded output pictures.

EEE 15. The method of EEE 3, wherein the source-picture interval scale factor parameter is specified using an absolute magnitude value of the scale factor and a sign flag of the scale factor.

EEE 16. The method of EEE 9, wherein the source picture timing parameters further include a source picture timing discontinuity flag, when set to 1 indicates that timing of source pictures corresponding to decoded output pictures is discontinuous.

EEE 17, The method of EEE 16, wherein the source picture timing parameters further include a source picture timing discontinuity type parameter and a source picture transition type parameter, wherein the source picture timing discontinuity type parameter indicates a discontinuity in source pictures according to a first table and the source picture transition type parameter indicates a transition type in the sources pictures according to a second table.

EEE 18. The method of EEE 4 wherein the source picture timing parameters further include a source type parameter, wherein the source type parameter indicates the timing relationship between source pictures and corresponding decoded output pictures.

EEE 19. The method of EEE 18, wherein the source type parameter may indicate one or more of: slow motion, sped-up motion, high-speed imaging, time-lapse imaging, temporal reversal, a still image, or sporadic imaging.

EEE 20. The method of EEE 19, wherein the source type parameter may not indicate both high speed imaging and time-lapse imaging. EEE 2L The method of EEE 18, wherein if the source type parameter is present, then the source- picture-interval (SourcePicturelnterval) value is further adjusted by a function of the source type value. EEE 22. The method of any one of EEEs 1-21, wherein the signaling section comprises a supplemental enhancement information (SEI) messaging section or a video user information (VUI) messaging section.

EEE 23. A tangible computer-readable storage medium having stored thereon computer- executable instructions for executing with one or more processors a method in accordance with any one of the methods recited in EEEs 1-2E

EEE 24. An apparatus comprising a processor and configured to perform any one of the methods recited in EEEs 1 -2 E

Claims

CLAIMS What is claimed is:

1. A method for decoding a video bitstream, the method comprising: receiving a coded video bitstream comprising an encoded picture section including an encoding of a sequence of video pictures and a signaling section including source picture timing parameters, wherein the source picture timing parameters comprise: a source-picture time-scale parameter indicating the number of time units passing in one second; and a source-picture number-of units-in-source-picture interval parameter indicating a number of time units of a clock operating at the frequency of the source-picture time-scale parameter; and decoding the sequence of video pictures based on the source picture timing parameters.

2. The method of claim 1 , further comprising computing a source-picture-interval (SourcePicturelnterval) value as the quotient of the source-picture number-of units-in sourcepicture interval divided by the source-picture time-scale.

3. A method for decoding a video bitstream, the method comprising: receiving a coded video bitstream comprising an encoded picture section including an encoding of a sequence of video pictures and a signaling section including source picture timing (SPT) parameters, wherein the source picture timing parameters comprise: a source-picture time-scale parameter indicating the number of time units passing in one second; a source-picture number-of units-in-elemental-source-picture interval parameter indicating a number of time units of a clock operating at the frequency of the source-picture time-scale parameter corresponds to an indicated elemental source picture interval of consecutive output pictures; and a source-picture interval scale factor parameter specifying a scale factor; and decoding the sequence of video pictures based on the source picture timing parameters.

4. The method of claim 3, further comprising: computing a source-picture-interval (SourcePicturelnterval) value as the multiplication product of an elemental source picture interval with the source-picture interval scale factor, wherein the elemental source picture interval is computed as the quotient of the source-picture number-of units-in-elemental-source- picture interval parameter divided by the source-picture time-scale parameter.

5. The method of claim 2 or claim 4, further comprising computing a source-picture time for picture n as:

6. The method of claim 3, wherein the source picture timing parameters further comprise a source picture sublayer maximum temporal ID identifying a maximum sublayer for which the SPT parameters apply.

7. The method of claim 3, wherein the source picture timing parameters further comprise: a source picture temporal sublayer ID for which SPT parameters apply; and a source picture sublayer delay factor which specifies a scale factor used in determining a temporal distance between a source picture corresponding to the first decoded output picture of a temporal sublayer having a value of Temporalld equal to 0 and a source picture corresponding to the first decoded output picture of temporal sublayer having a value of TemporallD equal to the source picture temporal sublayer ID.

8. The method of claim 7, further comprising computing a source-picture time for picture n as: SourcePictureTimef n ] = SourcePictureTimef previousPicInOutputOrder ] + SourcePicturelnterval +SublayerSourcePictureDelay, wherein picture n, n > 0, denotes an index of an output picture that is not the first output picture in the video bitstream and variable previousPicInOutputOrder denotes the last picture that is output that precedes picture n in output order (if any), and Sublayers ourcePictureDelay indicates the source picture sublayer delay factor.

9. The method of claim 3, wherein the source-picture interval scale factor parameter is specified for each one of N sublayers, wherein N > 0.

10. The method of claim 9, wherein the source picture timing parameters further comprise a source picture sublayer dyadic flag which if set to 1 indicates that temporal sublayers are coded in a dyadic relatationship and that the source-picture interval scale factor parameter specifying a scale factor syntax element is not present.

11. The method of claim 9, wherein the source picture timing parameters further include a source picture sublayer implicit timing flag which when set to 1 indicates that sublayer implicit timing type information is present for each of the sublayers.

12. The method of claim 9, wherein the source picture timing parameters further include a source picture sublayer synthesized picture flag for each one of the N sublayers, wherein, when set to 1 indicate that decoded output pictures belonging to the i-th temporal sublayer are synthesized and do not correspond to unmodified original source pictures.

13. The method of claim 9, wherein the source picture timing parameters further include a source picture timing type parameter which indicates a timing relationship between source pictures and corresponding decoded output pictures according to a mapping table.

14. The method of claim 9, wherein the source picture timing parameters further include a source picture-timing-equals-output-timing flag, which when set to 1 indicates that timing of source pictures is the same as the timing of corresponding decoded output pictures.

15. The method of claim 3, wherein the source-picture interval scale factor parameter is specified using an absolute magnitude value of the scale factor and a sign flag of the scale factor.

16. The method of claim 9, wherein the source picture timing parameters further include a source picture timing discontinuity flag, when set to 1 indicates that timing of source pictures corresponding to decoded output pictures is discontinuous.

17. The method of claim 16, wherein the source picture timing parameters further include a source picture timing discontinuity type parameter and a source picture transition type parameter, wherein the source picture timing discontinuity type parameter indicates a discontinuity in source pictures according to a first table and the source picture transition type parameter indicates a transition type in the sources pictures according to a second table.

18. The method of claim 4 wherein the source picture timing parameters further include a source type parameter, wherein the source type parameter indicates the timing relationship between source pictures and corresponding decoded output pictures.

19. The method of claim 18, wherein the source type parameter may indicate one or more of: slow motion, sped-up motion, high-speed imaging, time-lapse imaging, temporal reversal, a still image, or sporadic imaging.

20. The method of claim 19, wherein the source type parameter may not indicate both high speed imaging and time-lapse imaging.

21. The method of claim 18, wherein if the source type parameter is present, then the source- picture-interval (SourcePicturelnterval) value is further adjusted by a function of the source type value.

22. The method of any one of claims 1-21, wherein the signaling section comprises a supplemental enhancement information (SEI) messaging section or a video user information (VUI) messaging section.

23. A tangible computer-readable storage medium having stored thereon computer-executable instructions for executing with one or more processors a method in accordance with any one of the methods recited in claims 1-21.

24. An apparatus comprising a processor and configured to perform any one of the methods recited in claims 1-21.