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Thread: audio/video chunk sequence in avi file




audio/video chunk sequence in avi file
user name
2008-05-07 10:54:28
When I look at the mjpg avi file, audio and video are interleaved in movi. What is the rule for the audio and video chunk sequence?  is it like this:
 audio_chunk  for one period ( say x seconds )
 ;video_chunk1
 ;video_chunk2
 ;....
 all video_chunks for the play time equavlent to the previous audio_chunk ( x second )
 ;
 audio_chunk2
 video_chunks
.... ( all video_chunks for play time equavelent to audio_chunk2)
 
 ;
in other words, video chunks will not be encoded to place in avi file where it is ahead of its corresponding audio chunk. Is this correct?
 
Thank you so much!
 
Gerry
 
Re: audio/video chunk sequence in avi file
user name
2008-05-08 03:24:38
Hi,

Gerry Fan schrieb:
> When I look at the mjpg avi file, audio and video are
interleaved in 
> movi. What is the rule for the audio and video chunk
sequence?  is it 
> like this:
>  audio_chunk  for one period ( say x seconds )
>  video_chunk1
>  video_chunk2
>  ....
>  all video_chunks for the play time equavlent to the
previous 
> audio_chunk ( x second )
>  
>  audio_chunk2
>  video_chunks
> .... ( all video_chunks for play time equavelent to
audio_chunk2)
>  
>  
> in other words, video chunks will not be encoded to
place in avi 
> file where it is ahead of its corresponding audio
chunk. Is this correct?

There is no such rule. Audio chunks vary from one video
frame duration up to
1 second or so. I even saw an AVI file (DivX), which had all
video chunks
followed by all audio chunks. When I encode AVIs or
Quicktime, I make
the audio chunks about 0.5 seconds long.

Shorter audio chunks make seeking more efficient, longer
audio chunks decrease
the overhead. Software decoders usually never have problems,
hardware decoders
(like DivX players) might screw up, if the required buffer
size becomes to large.

Burkhard

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Re: audio/video chunk sequence in avi file
user name
2008-05-08 21:42:48
Thank you very much!

On 5/8/08, Burkhard Plaum < plaumipf.uni-stuttgart.de">plaumipf.uni-stuttgart.de> wrote:
Hi,

Gerry Fan schrieb:
&gt; When I look at the mjpg avi file, audio and video are interleaved in
> movi. What is the rule for the audio and video chunk sequence?&nbsp; is it
> like this:
>  ;audio_chunk &nbsp;for one period ( say x seconds )
>&nbsp; video_chunk1
&gt; &nbsp;video_chunk2
>&nbsp; ....
>&nbsp; all video_chunks for the play time equavlent to the previous
> audio_chunk ( x second )
>
>; &nbsp;audio_chunk2
>&nbsp; video_chunks
> .... ( all video_chunks for play time equavelent to audio_chunk2)
>
&gt;
> in other words, video chunks will not be encoded to place in avi
> file where it is ahead of its corresponding audio chunk. Is this correct?

There is no such rule. Audio chunks vary from one video frame duration up to
1 second or so. I even saw an AVI file (DivX), which had all video chunks
followed by all audio chunks. When I encode AVIs or Quicktime, I make
the audio chunks about 0.5 seconds long.

Shorter audio chunks make seeking more efficient, longer audio chunks decrease
the overhead. Software decoders usually never have problems, hardware decoders
(like DivX players) might screw up, if the required buffer size becomes to large.

Burkhard

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