EP1031157A1 - Mise en forme de signaux comprimes - Google Patents

Mise en forme de signaux comprimes

Info

Publication number
EP1031157A1
EP1031157A1 EP98952932A EP98952932A EP1031157A1 EP 1031157 A1 EP1031157 A1 EP 1031157A1 EP 98952932 A EP98952932 A EP 98952932A EP 98952932 A EP98952932 A EP 98952932A EP 1031157 A1 EP1031157 A1 EP 1031157A1
Authority
EP
European Patent Office
Prior art keywords
frames
coded frames
coded
prediction
bitstream
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98952932A
Other languages
German (de)
English (en)
Inventor
Michael James Knee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Snell Advanced Media Ltd
Original Assignee
Snell and Wilcox Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Snell and Wilcox Ltd filed Critical Snell and Wilcox Ltd
Publication of EP1031157A1 publication Critical patent/EP1031157A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/02—Editing, e.g. varying the order of information signals recorded on, or reproduced from, record carriers
    • G11B27/031—Electronic editing of digitised analogue information signals, e.g. audio or video signals
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T9/00—Image coding
    • G06T9/004—Predictors, e.g. intraframe, interframe coding
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/34—Indicating arrangements 
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/90—Tape-like record carriers

Definitions

  • This invention relates to the editing of compressed bitstreams and is particularly suitable for editing in the field using compact equipment.
  • the invention will find application with any compression system in which the bitstream itself is not easily edited, for example because it involves prediction to or from information at different points in time.
  • a well known example is the MPEG-2 video compression standard (ISO/IEC 131818-2), particularly when operated at low bit-rates with relatively long periods between intra-coded (I) pictures, that is to say pictures which do not rely upon prediction.
  • the sequence of picture types (I, P or B) is known as the Group of Pictures or GOP structure.
  • a method for editing MPEG-2 bitstreams which involves decoding, editing in the video domain and subsequent re-encoding, there being no loss arising in the cascading of decoding and re-encoding processes. This is achieved by carrying forward information about an upstream encoding process so that a downstream re-encoding process makes use of the same coding decisions (see for example W095/35268 and WO97/08898).
  • the present invention consists in one aspect in a method for use in the editing of compressed bitstream sequences which include intra- coded and prediction-coded frames each corresponding with a respective video frame, comprising the steps of identifying video frames to be represented in an edited bitstream sequence; selecting first coded frames which correspond with said identified video frames; selecting second coded frames which do not correspond with said identified video frames but which are required for prediction of any prediction-coded frames among said first coded frames; passing said first and said second coded frames through a channel; utilising said second coded frames to decode said prediction-coded frames among the first coded frames; and re-encoding the decoded frames to provide the edited bitstream sequence.
  • the channel in question may comprise - as examples - a communication link or a bitstream store. In either case, considerable advantage will be secured from avoiding the need to pass all coded frames. Since all necessary coded frames are passed, the edited bitstream sequence suffers no degradation.
  • the present invention consists in apparatus for use in the editing of compressed bitstream sequences which include intra-coded and prediction-coded frames each corresponding with a respective video frame, comprising an input bitstream source, an edit decision list terminal for receiving identification of video frames chosen for an edited bitstream output and frame selection means adapted to select in addition to first coded frames which correspond with said chosen video frames, those second coded frames which are required for prediction of any of said first coded frames.
  • the frame selection means is adapted to select in addition to first coded frames which correspond with said chosen video frames, those second coded frames and only those second coded frames which are required for prediction of any of said first coded frames.
  • the frame selection means is adapted to select in addition to first coded frames which correspond with said chosen video frames, contiguous sequences of coded frames which contain those second coded frames which are required for prediction of any of said first coded frames. Each such contiguous sequence may be selected dynamically to be of the minimum length necessary to ensure that all second coded frames are required. Alternatively, a fixed length can be determined - with reference to the known GOP structure - such that inclusion of all second coded frames is guaranteed.
  • Figures 1 and 2 are block diagrams illustrating two different theoretical approaches to the editing of compressed bitstreams, which are generated remotely; and Figure 3 is a block diagram of apparatus according to the present invention.
  • a browse track is a signal recorded alongside the main compressed signal which enables quick access to recorded segments on a tape or disk.
  • a browse track will have reduced resolution or quality.
  • An edit decision list records the results of an operator's edit decisions made using the browse track. It consists of a list of segments of recorded material together with precise descriptions of the editing operations to be performed.
  • the process of conforming an edit is to apply the EDL to the main recorded material to generate the final edited sequence in the same compressed format.
  • the portable equipment comprises an MPEG2 encoder 10, receiving video material from a source such as a camera.
  • a browse track generator 12 generates a browse track from the video material and the MPEG2 bitstream and browse track are recorded together on a disk, tape or other store 14.
  • a suitable user interface 16 is provided to enable the remote operator, viewing the browse track, to prepare an EDL. This is then stored in the EDL unit 18.
  • a browse track is generated and stored in the portable equipment, either at the time of acquisition or off-line.
  • this browse track could be a reduced-resolution version of the picture in which each frame is self-contained so that the usual "trick" modes such as fast-forward, fast rewind, pause and slow-motion replay can be performed as well as viewing of any proposed edit sequence at browse quality.
  • a graphical user interface again in accordance with prior art, is used to view the browse track and interpret the operator's decisions to form an EDL.
  • the edit conformer 20 receives the EDL and in communication with the store 14, generates an edited, compressed bitstream. The manner in which this achieved is known in itself and need not be described here.
  • the hardware represented by the edit conformer 20 is not available in a sufficiently miniaturised form for it to be included in any sensibly portable equipment.
  • the edit conformer 20 is situated not in the portable equipment, but in the studio. This necessitates the transmission of the originally recorded material and the EDL, to the studio. Transmission of the originally recorded material will typically demand high bandwidth (which may not be available in an economic manner) or transmission times that are inconveniently long.
  • What distinguishes the present invention is how the required material is selected for transmission. This is achieved in the "select required frames" block 22 which uses the EDL and knowledge of the GOP structure of the recorded material to determine precisely which frames of the recorded material need to be transmitted to the studio to enable the final edit to be conformed.
  • the example shows the I, P and B frames of the two sequences in display order. It will be remembered that I frames are intra-coded with no prediction, P frames are forward predicted from preceding I or P frames and B frames are forward and backward predicted. In the following representation, the underlined frames are those that are selected for transmission to the studio.
  • the final edited sequence will consist of frames from Sequence 1 up to the out point, followed by frames from Sequence 2 starting from the in point.
  • Sequence 2 ....P B B I B B P B B P B B B J P B B I B B P... in point
  • Sequence 1 all the frames up to and including the P-frame after the out point are transmitted to the studio because the MPEG-2 decoder in the studio will require access to that P-frame for prediction purposes.
  • Sequence 2 all the frames from the l-frame immediately before the in point are transmitted to the studio, because that l-frame and all the P-frames between it and the in point are required for prediction purposes.
  • two additional frames are transmitted from Sequence 1 and nine additional frames are transmitted from Sequence 2.
  • the selected frames can then be transmitted to the studio in real time at an average bit-rate only slightly higher than that recorded on the tape or disk. Alternatively, they can be transmitted at the recorded bit-rate slightly slower than real-time, or some other trade-off between transmission bit-rate and time can be found.
  • a refinement of the invention in which the number of additional frames to be transmitted is reduced further, is illustrated by the following example based on the same sequences as above. Again, the frames to be transmitted are shown underlined.
  • the number of additional frames following the out point and preceding the in point is fixed to a constant, for example the maximum number of frames in a GOP, that is known to embrace all possible cases. This would be simpler to implement but might increase the transmission bandwidth or time significantly if there are many edit points.
  • the underlined coded frames, together with the EDL, are transmitted (for example over a satellite link) to the studio where they are received by the edit conformer. This essentially operates to decode and then re-encode certain coded frames. Particularly, these will be prediction-coded frames which correspond to selected video frames but which rely for prediction on coded frames which do not correspond to selected video frames. In the sequence examples given above, the coded frames which will require to be decoded and re-encoded are shown underlined below:

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Television Signal Processing For Recording (AREA)
  • Compression Or Coding Systems Of Tv Signals (AREA)

Abstract

L'utilisateur d'un équipement vidéo portable à base MPEG est capable de produire une liste de décision de mise en forme (LDMF) sur place. Au moyen de cette liste et de la connaissance de la structure de groupe d'images, on sélectionne non seulement les trames directement requises dans LDMF, mais aussi les trames P et I s'appuyant sur des buts prédictifs. En transmettant ou en stockant uniquement ces trames sélectionnées plutôt que le matériau MPEG enregistré à l'origine, on fait des économies considérables. Dans le studio, les trames sélectionnées et LDMF sont utilisées pour former le train binaire MPEG désiré mis en forme.
EP98952932A 1997-11-12 1998-11-12 Mise en forme de signaux comprimes Withdrawn EP1031157A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GBGB9723893.5A GB9723893D0 (en) 1997-11-12 1997-11-12 Editing compressed signals
GB9723893 1997-11-12
PCT/GB1998/003400 WO1999024987A1 (fr) 1997-11-12 1998-11-12 Mise en forme de signaux comprimes

Publications (1)

Publication Number Publication Date
EP1031157A1 true EP1031157A1 (fr) 2000-08-30

Family

ID=10821956

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98952932A Withdrawn EP1031157A1 (fr) 1997-11-12 1998-11-12 Mise en forme de signaux comprimes

Country Status (4)

Country Link
EP (1) EP1031157A1 (fr)
AU (1) AU1047499A (fr)
GB (1) GB9723893D0 (fr)
WO (1) WO1999024987A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5148797B2 (ja) * 2000-02-08 2013-02-20 ソニー株式会社 映像データ記録装置および映像データ記録方法
US20050276573A1 (en) * 2004-05-28 2005-12-15 Abbate Jeffrey A Method and apparatus to edit a media file
US8522142B2 (en) 2005-12-08 2013-08-27 Google Inc. Adaptive media player size
US8214516B2 (en) 2006-01-06 2012-07-03 Google Inc. Dynamic media serving infrastructure
JP2009260933A (ja) 2008-03-17 2009-11-05 Toshiba Corp 動画素材編集装置とそのプログラム及び動画素材編集方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0845908B1 (fr) * 1994-06-17 2003-02-05 Snell & Wilcox Limited Compression d'un signal combiné à partir de plusieurs signaux vidéo comprimés et partiellement décodés
GB2296600B (en) * 1994-08-12 1999-04-07 Sony Corp Portable AV editing apparatus
JP3713715B2 (ja) * 1994-08-12 2005-11-09 ソニー株式会社 ビデオ信号編集装置
US5559562A (en) * 1994-11-01 1996-09-24 Ferster; William MPEG editor method and apparatus
WO1996026602A1 (fr) * 1995-02-23 1996-08-29 Avid Technology, Inc. Dispositif portable d'enregistrement d'images en mouvement comportant une commande de commutation pour des configuration de flux de donnees multiples

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9924987A1 *

Also Published As

Publication number Publication date
AU1047499A (en) 1999-05-31
GB9723893D0 (en) 1998-01-07
WO1999024987A1 (fr) 1999-05-20

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