WO2008064831A1 - Dispositif et procédé de détermination d'un décalage de code temporel - Google Patents

Dispositif et procédé de détermination d'un décalage de code temporel Download PDF

Info

Publication number
WO2008064831A1
WO2008064831A1 PCT/EP2007/010196 EP2007010196W WO2008064831A1 WO 2008064831 A1 WO2008064831 A1 WO 2008064831A1 EP 2007010196 W EP2007010196 W EP 2007010196W WO 2008064831 A1 WO2008064831 A1 WO 2008064831A1
Authority
WO
WIPO (PCT)
Prior art keywords
time code
time
pulse
signal
input
Prior art date
Application number
PCT/EP2007/010196
Other languages
German (de)
English (en)
Inventor
Michael Beckinger
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Publication of WO2008064831A1 publication Critical patent/WO2008064831A1/fr

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
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel

Definitions

  • the present invention relates to an apparatus and method for determining a time code offset of a time code signal from a smoothed time code signal, and more particularly to an analyzer, a so-called LTC analyzer, for measuring time code variations.
  • WFS Wave Field Synthesis
  • Every point that is detected by a wave is the starting point of an elementary wave that propagates in a spherical or circular manner.
  • Applied to the acoustics can be simulated by a large number of speakers, which are arranged side by side (a so-called speaker array), any shape of an incoming wavefront.
  • a so-called speaker array any shape of an incoming wavefront.
  • the audio signals of each loudspeaker must be fed with a time delay and amplitude scaling in such a way that the radiated sound fields of the individual loudspeakers are superimposed correctly.
  • the contribution to each speaker is calculated separately for each source and the resulting signals added together. If the sources to be reproduced are in a room with reflective walls, reflections must also be reproduced as additional sources via the loudspeaker array. The cost of the calculation therefore depends heavily on the number of sound sources, the reflection characteristics of the recording room and the number of speakers.
  • the advantage of this technique is in particular that a natural spatial sound impression over a large area of the playback room is possible.
  • the direction and distance of sound sources are reproduced very accurately.
  • virtual sound sources can even be positioned between the real speaker array and the listener.
  • a synchronization of the video and the various audio channels in the highest possible quality is required.
  • a standard time code is usually used for the cinema or studio operation.
  • LTC Longitudinal Time Code
  • the longitudinal time code is a time code that is typically exposed to the footage so that each frame gets its own time code.
  • FIG. 2 shows a sequence of individual images 200, 201, 202, 203, wherein the individual image 200 is designated as a single image EBi, while the individual image 201 is designated as a single image EBi + 1.
  • Fig. 2 effectively shows a "rolled-up" portion of a film having 24 frames per second in the example shown in Fig. 2.
  • a field 204 which is assigned to each individual image in the schematic representation of FIG. 2, the counting method of the long-term time code is shown.
  • the longitudinal time code consists of "time information" and "frame information" with regard to its encoded information.
  • the time information is shown schematically in FIG. 2 such that the individual image i (200) is an image whose time information z. 10 hours, 0 minutes and 1 second.
  • the frame information designates the first frame at that second for the image 200.
  • the frame information for the frame 202 denotes the 24th frame at the "time" of 10 hours, 0 minutes, and 1 second.
  • the film has a playback frequency of 24 frames per second (other playback frequencies also exist, such as 25 frames per second, for example)
  • the time information of the individual picture k + 1 (203) 10 hours, 0 minutes and 2 seconds while the frame Information of this frame is again equal to 1, since this is the first frame in the "new" second.
  • the starting point of the time information can be selected arbitrarily. For example, if the starting point of the time information is set to zero and a movie lasts 90 minutes, the maximum time information will be 1 hour, 30 minutes, 0 seconds.
  • Essential in the time information is the fact that each frame receives an original time code information, which makes it possible to reconstruct the position of each frame in the sequence of frames, ie in the film.
  • the time information and the frame information are both coded together by means of the time code, which can be arbitrarily selected, and the z. B. is an 8-bit code of binary zeroes and ones.
  • the z. B. is an 8-bit code of binary zeroes and ones.
  • a binary zero a dark spot on the film can be exposed
  • a binary one a light spot on the film can be exposed or vice versa.
  • it is also possible and well established in practice to use a "zero" e.g. to encode as two short light / dark changes and to encode a "one" as a long light / dark change.
  • each frame is assigned 2000 discrete audio samples. These samples are typically stored externally in files and synchronized in the film playback to the individual images digital / analog-converted, amplified and delivered to the appropriately positioned speakers, for example in the cinema.
  • word clock a centrally generated and generally stable clock
  • the frequency of this word clock is equal to the frequency at which the stored discrete samples were sampled.
  • Fig. 3 shows an embodiment in which video data and audio data corresponding to the time codes are allocated along a time beam.
  • a time code ZC1 sets a time ti at which a video page 1 is displayed and at the same time ti also marks a beginning of audio frames 1, ie a first set of audio frames.
  • the Audio frame 1 thereby encode the audio signal which has been received between the time code ZCL at time ti and the time code ZC2 at the time T 2.
  • the audio frames 1 generally contain a plurality of independent audio signals, of which an audio signal Audio 1 and an audio signal Audio 2 are shown here, and as described above, the audio signal is sampled, for example, at the word clock frequency WC.
  • the video page 1 is replaced by a video page 2, and at the same time the time t 2 is also a beginning of the audio frames 2, which in turn different generally independent audio signals (audio 1, audio 2, audio 3, ...) include.
  • These data, ie the video page 2 and the audio frames 2 contain the time code ZC2 which marks the start time along the time line.
  • This scheme continues for the following video and audio data which, for example, begin at a time t 3 and are identified by a time code ZC3.
  • the distances between the time codes and the video and audio material shown in FIG. 3 are shown here for the sake of better illustration only, and do not involve a temporal pause between the time codes and the video and audio material. Rather, the time codes can be removed after the chronological juxtaposition of the audio and video data.
  • FIG. 4 shows an embodiment of how a device for decoding and synchronizing 210 converts input signals 220, which may comprise digital non-synchronous video and audio data, into synchronous analog video and audio data 230.
  • the input signals 220 may be read from a data carrier one after the other or at the same time. Possible data carriers are, for example, a CD, a DVD or even a hard disk and generally provide encoded digital data for a video signal and for several audio signals.
  • the input data 220 may thus be input in parallel or in series to the means for decoding and synchronizing 210 where the data is analyzed and arranged so that all the audio and video data 230 can be output for a given time.
  • the various audio and video signals thus require a time code signal which assigns audio data of the various channels to a video picture. It is obvious that as the number of audio channels increases, the requirements for recording and playback also increase in terms of high-quality synchronization.
  • LTC Longitudinal Time Code
  • time code signal is to be synchronized to a word clock signal, ie when the audio sampling rate is to be matched to the time code. It happens, for example, in studios, that a time code and a word clock do not fit optimally to each other, because, for example, conventional synchronizers can not deliver fast enough with strongly fluctuating time code to a matching word clock.
  • the present invention is based on the recognition that the quality of a time code can be determined by examining the time code with regard to its fluctuations in comparison with a smoothed time code.
  • the smoothed time code is according to the invention a synchronization time code, which is generated by a time code sheets and can be used synchronized for the synchronization of different audio and video signals.
  • time code fluctuations within a tolerance width ⁇ result in neither visual nor audible effects, it is sufficient to use a synthesis time code as the synchronization time code, which can be generated, for example, from a highly accurate time base. However, for larger variations, it is important to lengthen or shorten this synthetic timecode accordingly to avoid audible artifacts. If only relatively few corrections or modifications of the synthesis time code are required, such a smoothed time code can be generated very quickly in high quality.
  • a time code of relatively high quality is thus characterized by the fact that it can vary within the tolerance width ⁇ , but only relatively rarely does the tolerance wide ⁇ injured.
  • Another aspect in the quality assessment of sound recording environments or studio equipment is an examination of the compatibility of word clock signals or word clock pulses and time code signals. It is determined how far both clocks are synchronized, so that a gap between two consecutive time code signals always contains the same number of word clock pulses.
  • a sync pulse is output at the beginning of an incoming time code, with the aid of which a frequency counter can determine the word clock pulses per time code frame.
  • the word clock pulses can fluctuate between two time code signals within a certain range of variation without generating audible interference.
  • a high-quality recording studio environment or high-quality studio equipment is characterized by a relatively small fluctuation range, or high-quality studio equipment only rarely violates a tolerable fluctuation range.
  • a measuring device LTC analysis device
  • a measuring method is provided in order to be able to determine the quality and synchronicity of time codes or time code encoders in connection with word clocks.
  • To measure the quality of fluctuations such as an LTC time code a time average of an LTC signal can be formed, with which the incoming time code is compared. The time differences of the incoming LTC packets can then be evaluated.
  • An advantage of the present invention is that the quality determination or the measurement of studio equipment takes place in such a way that above all fluctuations are detected which would lead to audible or visible artifacts. This can be used to determine what effort is necessary to generate a suitable signal for synchronization.
  • the quality is the higher, the fewer corrections are required to produce a smoothed time code signal or word clock encoder. Although an ideal time code signal may have variations, all variations are within the tolerance width ⁇ and thus can be neglected in terms of audiovisual impression.
  • measuring devices can be produced inexpensively and used flexibly.
  • the measuring method according to the invention can be integrated in measuring devices and the measuring devices can be used in all digital studios.
  • the appropriate LTC analyzers can also be used to measure studios.
  • measurements of time code fluctuations become more and more important even in nonsynchronous networks such as Ethernet.
  • time code variations can be examined for their audiovisual relevance.
  • manufacturers of time code analyzers can easily and quickly integrate the method according to the invention into their products.
  • FIG. 1 is a schematic representation of a device according to the invention for determining a time code offset
  • Fig. 2 is a schematic representation of a typical linear time code
  • Fig. 3 is a timing chart in which video and audio data corresponding to the time codes are synchronized
  • FIG. 4 shows a schematic representation of a synchronization of audio and video data
  • FIG. 6 is a block diagram of an apparatus for synchronizing to a smoothed time code signal
  • Fig. 7 is a detailed illustration of the functionality of a comparator and a time code manipulator of Fig. 6;
  • Fig. 8 is a schematic diagram for the generation of a manipulated time code signal
  • FIG. 9 shows a detailed representation of a first device according to the invention for analyzing the
  • FIG. 10 shows a detailed representation of a second device according to the invention for analyzing the time code by means of a PLL circuit.
  • the device according to the invention has a time code generator 110 which outputs the time code signal 105 at an output.
  • the time code signal 105 is input to a time code 120 and to a first input of a time code comparator 130.
  • the time code 120 has a further input for a time base 140 and also a time code output for outputting the time base 150 smoothed by the time base 140 smoothed time code 150 is output from the time code 120 to a second input of the time code comparator 130.
  • the time code comparator 130 compares the time code signal 105 with the smoothed time code signal 150 and determines the time code offset 160 from a deviation of the time code signal 105 from the smoothed time code 150.
  • the time code offset 160 is provided by the time code comparator 130 for display, further processing, or storage, for example output.
  • the time code signal 105 output from the time code generator 110 may be obtained from various sources.
  • the film material or the audio material which is stored for example on a CD or DVD, has a time code stamped on it for each different channel.
  • the impressed time code or the differences of successive time codes should correspond to the corresponding lengths of coded audio signals.
  • the time code generator 110 can also receive one or more time code clocks directly from recording devices. For example, sound or video recording devices obtained.
  • the device according to the invention can directly measure, analyze or even compare the quality of time code generators of the recording devices.
  • FIG. 2 shows one possible design of the time code signal 105 for an embodiment based on the playback of 24 frames (or frames) per second.
  • FIG. 3 shows a timeline along which audio and video data are time ordered according to their time code.
  • the section belonging to a time code ZCi is also called an LTC frame.
  • FIG. 4 shows 210 data from various sources 220 as a means for synchronizing arranges synchronously so that output signals 230 can be forwarded in parallel to different speakers or an image projection device.
  • Fig. 5 shows an example of variations of a time code signal.
  • This frequency can be for example 24 Hz, ie 24 pictures are called in one second. Other frequencies are also possible, such as 25 frames per second.
  • This fundamental frequency is denoted by fo in FIG.
  • the time code signal obtained may vary with time, ie the corresponding frequency has temporal variations around the value fo and is therefore generally not constant. These variations are shown in the graph of FIG. 5. As already explained, fluctuations within a certain tolerance range 2 ⁇ are acceptable, provided that the tolerance range 2 ⁇ includes fluctuations which do not lead to any audible or visible effects.
  • the tolerance range 2 ⁇ is limited by an upper tolerance limit 510 and a lower tolerance limit 520, which is in each case identified by a dashed line.
  • the upper tolerance limit 510 and the lower tolerance limit 520 deviate by the same value from the fundamental frequency fo, ie the upper tolerance limit 510 corresponds to a frequency of fo + ⁇ and the lower tolerance limit 520 corresponds to a frequency of fo ⁇ ⁇ ,
  • the upper tolerance limit 510 or the lower tolerance limit 520 may each deviate from the fundamental frequency f 0 by different values.
  • the frequency f of the time code signal varies for the times t ⁇ Ti and for the times T 2 ⁇ t ⁇ T 3 and for the times t> T 4 within the tolerance range 2 ⁇ between the upper tolerance limit
  • fluctuations in the frequency f of the underlying time code signal are outside the tolerance range 2 ⁇ and should be audible or audible Avoiding, changing or adjusting effects.
  • FIG. 6 shows an exemplary embodiment of the time code slicer 120.
  • a device 610 for detecting the time code exposed for the sequence of individual images supplies on the output side a sequence of acquired time codes.
  • the detected time code is, for example, the time code 105 from the time code generator 110, which may have the device 610, for example.
  • the apparatus shown in FIG. 6 further comprises a time code generator 612 configured to generate a sequence of synthesis time codes from a seed value.
  • the seed is provided from the sequence of detected time codes at the output of the device 610 by a decoder 614 for decoding a time code of the detected sequence of time codes.
  • the time code generator 612 produces on the output side a sequence of synthesis time codes.
  • the synthesis time codes can be generated, for example, by means of a high-precision time base which is either part of the time code generator 612 or connected via an input 140 and, like the sequence of detected time codes, is fed to a comparator 616 at the output of the device 610.
  • the comparator 616 is designed to perform preferably for each pair of detected time code and corresponding synthesis time code, that is for a detected time code for the frame i, for example, and the synthesis time code for the frame i, for example, a phase comparison to determine whether the two time codes in time offset, that is out of phase, or temporally coincide more or less.
  • the detected time code will not have a particularly well-defined signal shape to which audio processing devices can safely synchronize. Nevertheless, a minimum of rising and falling flanks will be detectable. Should the detected time code be severely corrupted, this being due to the fact that its shape is known and corresponds exactly to the shape of the parallel synthesis time code, it is still possible to perform reconstruction for phase comparison purposes.
  • the time code typically extends over the entire frame on the film and therefore has a plurality of rising and falling edges in a pattern defined by the time code itself.
  • phase comparison Since only a single edge or a single zero crossing is required in principle for the phase comparison (if the position of the edge is known in the time code itself), a phase comparison will also be feasible in the case of strongly corrupted time codes. Should a time code be so strongly corrupted that no phase comparison is feasible, then this is also unproblematic, since then with the parallel synthesis time code no manipulation is performed and the comparison for the next detected time code in the sequence with the next synthesis time code in the sequence is carried out again, and until such time as a detected time code has been determined again, based on which a successful phase comparison is possible.
  • the comparator 616 determines that there is a phase deviation between a pair of detected time code and synthesis time code which exceeds a predetermined deviation threshold in absolute value, an acknowledgment signal (yes) is sent to a time code manipulator 620 on an output line 618 output, the time code manipulator will manipulate the current synthesis time code at which this deviation has been detected and provided via a line 622 to the time code manipulator 620. If a No signal is transmitted via the line 618 from the comparator 616 to the manipulator 620, the currently considered synthesis time code is not manipulated and simply forwarded as synthesis time code to an audio processing device 624 for synchronization purposes.
  • the time code manipulator 620 is thus configured to change a time length of a synthesis time code of the found synthesis time codes to obtain a manipulated synthesis time code if the comparator 616 detects a phase deviation between a time code of the detected sequence of time codes and a synthesis time code. Determines time code, the amount exceeds a predetermined deviation threshold. The change in the time length of the synthesis time codes occurs such that a phase deviation between a synthesis time code following the manipulated synthesis time code and a corresponding detected time code is reduced.
  • the manipulated synthesis time code is, for example, the smoothed time code 150.
  • the synthesis time code is manipulated to be extended if the synthesis time code generator 612 has run too fast compared to the sequence of detected time codes. If the synthesis time code generator 612 has run too slowly compared to the detected sequence of time codes, the Manipulation of a synthesis time code consist in a shortening of the standard time code normally output by the time code generator.
  • the audio processing device 624 is designed to execute a time-controlled provision of the predetermined number of discrete samples of the audio signal associated with a single image when the audio processing device detects a synthesis time code or a manipulated synthesis time code, respectively Single image is assigned.
  • synchronization is performed for each frame.
  • synchronization can also be performed only for every second, third, fourth, etc. single image, for example. This can be achieved by always taking into account only certain time codes from the sequence of synthesis time codes and manipulated synthesis time codes from the audio processing device 624. Alternatively, however, a corresponding functionality could be achieved that only for each z.
  • B. fourth detected time code, a synthesis time code or manipulated synthesis time code is generated.
  • a first step 730 the comparator reads in a detected time code i and a corresponding synthesis time code i relative to a reference time, such as an event in a clock cycle of a word clock, which will be discussed later.
  • a clock event for example, a rising edge, a falling edge or, depending on the embodiment, a zero crossing of the word clock can be used.
  • a phase comparison of the time codes is made to determine if there is a phase offset between the synthesis time code and the detected time code.
  • the detected time code typically does not have a particularly beautiful shape, since it has been optically read, for example. In particular, it is subject to jitter and noise.
  • the synthesis time code since it has been generated by its own digital synthesis time code generator (for example, by the high-precision time base 140), has a defined, clearly specified shape in terms of edge steepnesses that are neither noise nor jittery.
  • phase comparison can therefore take place in such a way that it is determined whether the synthesis time code is shifted in time with respect to the detected time code either in the positive or in the negative direction, ie has a positive or negative phase offset. If this phase comparison, which is performed in a step 732 of FIG. 7, yields a phase deviation that is above a threshold, which is decided in a decision box 734, then a step 736 is entered, which will be discussed below. However, if decision block 734 determines that the deviation is below the threshold, then step 730 for the pair of next detected time code and next Synthesis time code performed, which is represented symbolically by the incrementation box 738.
  • the synthesis time code comes too early, that is, whether the time code generator 612 is running too fast with regard to the detected time codes detected. If so, the synthesis time code is extended, preferably by inserting only a single word clock period, preferably at the end of the synthesis time code. On the other hand, if it is determined that the synthesis time code comes too late, so that the time code generator 612 of Fig. 6 is too slow in the sequence of detected time codes, the synthesis time code that gave the phase deviation is shortened. This preferably occurs by restarting the time code generator 612, as schematically shown by a dashed line 626 in FIG. 6, with the start value valid for the next time code.
  • the extension or shortening of a synthesis time code is therefore typically expressed by the fact that the last pulse of the time code becomes slightly shorter or slightly longer.
  • this is not a problem for a time code decoder when considering real conditions. Assuming that frames are played at a frequency of 24 Hz, and that a time code extends over an entire frame, and that a time code has a length of 8 bits, wherein two time code clock periods are due for each bit, this is The frequency of the signal underlying the time code is about 384 Hz.
  • the word clock that drives the synthesis time code generator is typically 48 kHz. This means that a word clock period falls on a time code clock period.
  • FIG. 8 shows a schematic time beam representation for a generation of a smoothed time code signal 150, which preferably corresponds to the previously described manipulated synthesis time code.
  • the sequence of synthesis time codes is generated using the time base 140.
  • the sequence of synthesis time codes corresponds to the times ti, t 2 , t 3 , t 4 , etc.
  • the detected sequence of time codes corresponds to the read-in time code signal 105 with a first clock pulse at time ti, a second clock pulse at time t 2 , a third clock pulse at time t3 and a fourth clock pulse at time t. 4
  • the clock pulses of the time code signal 105 generally do not match the synthesis time code signal. At time ti, this happens to be the case, but the second clock signal t 2 is at a later time than the clock signal from the synthesis time code t 2 .
  • the time £ 3 of the third clock pulse of the time code signal 105 is before the time t 3 of the synthesis time code.
  • both the second clock signal of time code signal 105 at time t 2 and the third clock signal of time code signal 105 at time ⁇ 3 are within a tolerance range represented by dashed lines 810 and time ranges ti ⁇ ⁇ at times ti of synthesis Time codes extends.
  • the tolerance range in turn, preferably includes a range of variation within which audio-visual impairments can not be determined.
  • the fluctuation width (2 ⁇ ) in this time representation corresponds to the fluctuation width 2 ⁇ of FIG. 5 in the frequency representation.
  • the fourth clock pulse of the time code signal 105 at time t 4 outside the tolerance range ie t 4 > t 4 + ⁇ . Since such a shift is not tolerable, a modification is required for this clock pulse.
  • the modification is shown in Fig. 8 in the diagram shown below.
  • the time code signal 105 was within the tolerance range, which is shown by the dashed lines 810. Since such deviations are tolerable, the time code signal need not be modified, and thus the modified time code signal coincides with the synthesis time code signal at times ti, t 2 , t 3 .
  • the synthesis time code is shifted such that the modified time code signal occurs at time t 4 .
  • the time t 4 is chosen such that the time code signal 105 is again within the tolerance range of ⁇ ⁇ , ie I t 4 - t 4
  • This procedure which is preferably performed by the method shown in Figure 7, continues for all other clock pulses, i. all further pulses of the time code signal 105 are compared with the synthesis time code.
  • the latter is possibly shifted either to larger values, as was the case, at time tu or else, in the opposite case, the modified time code is shifted to smaller values.
  • the shift again occurs such that the time code signal 105 coincides with the modified time code signal within the tolerance range of ⁇ ⁇ .
  • the modified time code thus determined is used to synchronize the video and the individual audio channels.
  • time code blade 120 receives a sequence of time codes LTC1 from the time code generator 110 and simultaneously receives a time signal 140 from a high-precision time base 910.
  • the time code 120 generates, as described for example in Figs. 6-8, a smoothed time code LTC2 and passes this to the time code comparator 130 on.
  • the time code comparator 130 receives the modified time code LTC2 through the first input and at the same time the time code comparator 130 receives the original time code LTC1 through the second input. From the original time code LTCl and the smoothed timecode LTC2, the time code comparator 130 determines a time code offset 160 and outputs it to a display and storage device 920.
  • FIG. 1 The embodiment of FIG.
  • a high accuracy frequency counter 930 having a wordclock input to which a wordclock pulse 940 is applied through a wordclock encoder 940. Furthermore, the frequency counter 930 has a trigger input at which the time code comparator 130 sends trigger pulses. Further, the frequency counter 930 has an output at which the word clock pulses per time code interval are output and forwarded to a device for display 950. As high-precision time base 910 and frequency counter 930 are to be understood devices which have the highest possible quality.
  • LTC9 thus shows a basic measurement setup for measuring LTC fluctuations.
  • the LTC signal sequence of time codes
  • LTCl to be measured is compared to itself by a smoothing algorithm. This creates a new signal LTC2.
  • a time constant for example ⁇ from FIG. 8
  • the reaction speed can be set to synchronism fluctuations.
  • the time difference between the two LTC signals can be recorded by a display or written to a file to record a time course or to form an average value.
  • the time difference or the time code offset 160 of the time code signals 105 can be detected and evaluated with regard to various methods.
  • an optional evaluation unit can use conventional statistical methods and determine, for example, the standard deviation or the mean fluctuation range in order to obtain quality statements with regard to the time code generator 110.
  • fluctuations in the time code generator 110 per se are disadvantageous for audiovisual perception only if they are above a certain threshold, ie outside the tolerance range described above. They are. Therefore, it may be advantageous to detect only those fluctuations or deviations that violate this tolerance range when displaying or evaluating the time code offset 160 or the time difference.
  • both the maximum occurring time difference and a number are recorded, how often violations of the tolerance range within one second or or a fixed predetermined time interval occur.
  • either the time code signal LTC1 or the smoothed time code signal LTC2 may drive a pulse generator which sends a short trigger pulse for each start bit of an LTC frame (at time ti in FIG. 3).
  • This trigger pulse is used as a trigger for a frequency counter 930 which counts the word clock pulses WC per LTC frame. This can be used to check how many word clock pulses occur per time code frame.
  • the smoothed time code signal LTC2 By comparing with the smoothed time code signal LTC2, the deviation of the sample rate from the LTC signal can be determined.
  • a part of the embodiment of FIG. 9, such as the time code sheets 120, the time code comparator 130, the means for displaying and storing 920 may also be implemented in a computer with corresponding PC software.
  • the wordclock pulses per LTC frame be as close to the desired value as possible. Within a tolerable fluctuation range, however, smaller deviations can also be tolerated here. However, it does record a high quality recording device that the word clock pulses per LTC frame almost always coincide with the desired value.
  • the time code generator 110 outputs a sequence of time codes to a pulse converter 970, which generates a pulse 1 from the time code signal LTC from the time code generator 110.
  • the PLL circuit 960 has, for example, a phase-locked loop and can be used for clock synchronization.
  • the PLL circuit 960 receives the pulse 1 from the pulse converter 970 and also smoothing parameter 990, based on which the pulse 1 is smoothed by the pulse converter 970 and a pulse 2 is output.
  • the pulse 2 of the PLL circuit 960 is passed to a pulse comparator 980, which reads the pulse 2 at a first input and also receives the pulse 1 from the pulse converter 970 at a second input.
  • a pulse comparator 980 both pulses, ie pulse 1 and the smoothed pulse 2, are compared and the time code offset 160 determined, which is subsequently output to a device 920 for storage and display.
  • the pulse 1 of the pulse converter 970 also serves as a trigger pulse for the frequency counter 930 which, as in the embodiment described in Fig. 9, receives the word clock signal from a word clock 940 and from this the word clock pulses per time code interval (LTC). Frame) and outputs 950 on a display.
  • the trigger pulse used at the frequency counter 930 in this embodiment is identical to the pulse 1 generated in the pulse converter 970 from the time code signal LTC.
  • the means 920 and 950 for display may perform a quality assessment based, for example, on the number and magnitude of the fluctuations and using conventional statistical methods.
  • the exemplary embodiment of FIG. 10 is particularly advantageous in that PLL circuits are available in high quality and thus cost-effectively produce the device according to the invention. is adjustable. Furthermore, this embodiment has a high robustness.
  • Fig. 10 shows the basic measurement setup for measuring LTC fluctuations as a hardware-based solution.
  • the time code signal LTC to be measured drives a pulser 970, which sends a short pulse to each start bit of an LTC frame, resulting in a pulse train.
  • the pulse train is time-smoothed by the PLL circuit 960 with corresponding smoothing parameters 990.
  • the pulse comparator 980 compares, measures and displays the time offset of the pulses closest to the time. This allows the time jitter of a time code to be measured.
  • the measurement of the deviation of the sample rate from the LTC signal, i. the measurement of the word clock pulses per LTC frame can be calculated analogously to the embodiment of FIG. 9.
  • the embodiment described in FIG. 10 shows an implementation of a time code analyzer based on known hardware components.
  • the present invention describes an apparatus and method for analyzing time code variations of time codes imprinted, for example, on audio and video material for the purpose of synchronization, thus measuring, for example, studio equipment or an entire studio environment.
  • the present invention is particularly advantageous in that the quality determination or the measurement of studio equipment is such that, in particular, fluctuations are detected which would lead to audible or visible artifacts.
  • By evaluating, for example, the fluctuation range of the time code around the smoothed time code or the fluctuations of the word clock transmitter it can be ascertained which expenditure is necessary in order to generate a suitable signal for a synchronization.
  • the quality is the higher, the fewer corrections are required to produce a smoothed time code signal or word clock.
  • measuring devices according to the invention are inexpensive to manufacture and flexible.
  • the measuring method according to the invention can be integrated in measuring devices and the measuring devices can be used in all digital studios.
  • the appropriate LTC analyzers can also be used to measure studios.
  • measurements of time code fluctuations become more and more important even in nonsynchronous networks such as Ethernet.
  • time code variations can be examined for their audiovisual relevance.
  • manufacturers of time code analyzers can easily and quickly integrate the method according to the invention into their products.
  • the inventive scheme can also be implemented in software.
  • the implementation may be on a digital storage medium, in particular a floppy disk or a CD with electronically readable control signals, which may interact with a programmable computer system such that the corresponding method is executed.
  • the invention thus also consists in a computer program product with program code stored on a machine-readable carrier for carrying out the method according to the invention when the computer program product runs on a computer.
  • the invention can thus be realized as a computer program with a program code for carrying out the method when the computer program runs on a computer.

Landscapes

  • Signal Processing For Digital Recording And Reproducing (AREA)

Abstract

L'invention concerne un dispositif de détermination d'un décalage de code temporel (160) d'un signal de code temporel (105) par rapport à un signal de code temporel lissé (150), comportant un transmetteur de code temporel (110) pourvu d'une sortie de code temporel pour l'émission du signal de code temporel (105), un lisseur de code temporel (120) pourvu d'une entrée de code temporel (120), d'une entrée de base temporelle (140), et d'une sortie de code temporel pour l'émission du code temporel (150) lissé par rapport à la base temporelle (140). Le dispositif selon l'invention comporte également un comparateur de code temporel pourvu d'une première entrée, d'une deuxième entrée et d'une sortie pour le décalage de code temporel (160), la sortie de code temporel du transmetteur de code temporel (110) étant connectée à l'entrée de code temporel du lisseur de code temporel (120) et à la première entrée du comparateur de code temporel (130), la sortie de code temporel du lisseur de code temporel (120) étant connectée à la deuxième entrée du comparateur de code temporel (130), et le comparateur de code temporel (130) déterminant le décalage de code temporel (160) à partir d'une déviation du signal de code temporel (105) par rapport au signal de code temporel lissé (150).
PCT/EP2007/010196 2006-11-28 2007-11-23 Dispositif et procédé de détermination d'un décalage de code temporel WO2008064831A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE200610056159 DE102006056159B4 (de) 2006-11-28 2006-11-28 Vorrichtung und Verfahren zum Ermitteln eines Zeitcodeversatzes
DE102006056159.7 2006-11-28

Publications (1)

Publication Number Publication Date
WO2008064831A1 true WO2008064831A1 (fr) 2008-06-05

Family

ID=39311006

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2007/010196 WO2008064831A1 (fr) 2006-11-28 2007-11-23 Dispositif et procédé de détermination d'un décalage de code temporel

Country Status (2)

Country Link
DE (1) DE102006056159B4 (fr)
WO (1) WO2008064831A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004105034A1 (fr) * 2003-05-20 2004-12-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. Systeme et procede pour synchroniser un signal audio avec un film
US20050175197A1 (en) * 2002-11-21 2005-08-11 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Audio reproduction system and method for reproducing an audio signal

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5693159A (en) * 1979-12-25 1981-07-28 Sony Corp Error correcting system for advance data
JPS57123578A (en) * 1981-01-22 1982-08-02 Sony Corp Error correcting circuit for drive data
DE3577381D1 (de) * 1984-09-19 1990-05-31 Victor Company Of Japan Geraet zur synchronisierung verschiedener fernsehsysteme.
WO1994024817A1 (fr) * 1993-04-16 1994-10-27 Avid Technology, Inc. Procede de synchronisation d'un flux de donnees video avec un flux de donnees audio, et appareil associe
DE19513988A1 (de) * 1995-04-13 1996-10-17 Delta System Studioanlagen Gmb Verfahren zur Nachbildung bandbegrenzter analoger Bitmuster auf digitaler Ebene
US7551647B2 (en) * 2004-07-19 2009-06-23 Qvidium Technologies, Inc. System and method for clock synchronization over packet-switched networks
US7778173B2 (en) * 2005-01-04 2010-08-17 Cisco Technology, Inc. Clock recovery algorithm for remultiplexing MPEG-2 SPTSs and/or MPTSs in the presence of network jitter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050175197A1 (en) * 2002-11-21 2005-08-11 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Audio reproduction system and method for reproducing an audio signal
WO2004105034A1 (fr) * 2003-05-20 2004-12-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. Systeme et procede pour synchroniser un signal audio avec un film

Also Published As

Publication number Publication date
DE102006056159B4 (de) 2008-08-21
DE102006056159A1 (de) 2008-05-29

Similar Documents

Publication Publication Date Title
DE10322722B4 (de) Vorrichtung und Verfahren zum Synchronisieren eines Audiossignals mit einem Film
DE3020882A1 (de) Verfahren und vorrichtung zum edieren von digitalsignalen
DE2104622C3 (de) Verfahren und Schaltungsanordnung zur Synchronisation von Signalen
DE2353073A1 (de) Verfahren und einrichtung zur aufnahme und wiedergabe von fernsehbild und -ton mittels rotierender platten
DE69734548T2 (de) Verfahren und Vorrichtung zur magnetischen Wiedergabe
DE3405910C1 (de) Verfahren zur Steuerung eines Videobandgeraetes zum automatischen Auffinden von bespielten Videobandabschnitten sowie Videobandgeraet zur Durchfuehrung des Verfahrens
EP1894198A1 (fr) Dispositif et procede pour realiser une correlation entre un signal de son d'essai qui peut etre produit avec une vitesse variable, et un signal de son de reference
DE1412718B1 (de) Magnetbandsystem zur Wiedergabe eines aufgezeichneten Farbfernsehsignals
DE3238119C2 (de) Einrichtungen zur Verarbeitung einer digitalen Darstellung eines Analogsignals und zur Rückumwandlung der verarbeiteten Digitaldarstellung in die Analogform
DE102006056159B4 (de) Vorrichtung und Verfahren zum Ermitteln eines Zeitcodeversatzes
DE10254405B3 (de) Empfänger und Verfahren zum Betreiben eines Empfängers
DE102005045628B3 (de) Vorrichtung und Verfahren zum Ermitteln einer Stelle in einem Film, der in einer zeitlichen Folge aufgebrachte Filminformationen aufweist
DE102005035216A1 (de) Playback-Vorrichtung zur Synchronisation eines Playback eines Video-Signalanteils und eines Audio-Signalanteils eines AV-Signals und Verfahren dafür
EP1872368B1 (fr) Dispositif et procede pour detecter un emplacement dans un film
DE2938246C2 (de) Schaltungsanordnung zum Feststellen des Anfangspunktes von Datenpaketen aus digitalen Signalen und Synchronisierungssignalen
EP0185692B2 (fr) Procede pour diminuer la receptivite aux erreurs dans un signal audio numerique
WO2019121904A1 (fr) Procédé de synchronisation d'un signal supplémentaire avec un signal principal
DE10354973B3 (de) Verfahren zum Ermitteln von Laufzeitunterschieden zwischen Bild- und Tonsignalen auf Fernseh-Übertragungsstrecken
DE3790203C2 (fr)
DE2431988B2 (de) Einrichtung zur zeitsynchronen aufbereitung von parallel zur nutzinformation eingespeicherten steuersignalen
DE60030312T2 (de) Verfahren zum aufnehmen, wiedergeben oder darstellen von digitalen oder analogen, abgetasteten oder ununterbrochenen audio- und/oder video-afnahmen
DE2948785C2 (de) Vertikalsynchronsignal-Detektorschaltung
EP0602469A2 (fr) Méthode d'enregistrement sur bande magnétique à pistes obliques
DE2116191C (de) Phasensynchronisationsanordnung
AT520998A1 (de) Verfahren zum Synchronisieren von einem Zusatzsignal zu einem Hauptsignal

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 07846796

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07846796

Country of ref document: EP

Kind code of ref document: A1