[FFmpeg-devel] [PATCH] av_get_delay

Michael Niedermayer michaelni at gmx.at
Thu Jun 30 16:40:14 CEST 2011

On Thu, Jun 30, 2011 at 10:17:52AM -0400, Mike Scheutzow wrote:
> Michael Niedermayer wrote:
>> On Thu, Jun 30, 2011 at 09:22:04AM -0400, Mike Scheutzow wrote:
>>> Michael Niedermayer wrote:
>>>>>> This doesnt seem to work very well for example when you have:
>>>>>> a slideshow with commentary, the delay from the video stream could
>>>>>> make quite big jumps an be constant between them. It might be
>>>>>> better to add the remaining duration of the currently displayed frame
>>>>>> in there or something
>>> This is a very different use case than the original proposal was 
>>> meant  to solve, which I understood as pre-skewing uncompressed 
>>> output samples  to improve lip sync.
>> you seem to missunderstand this somehow.
> Well, it seems that you do not understand the problem that Nicolas is  
> trying to improve. Do you agree with these statements:

you replied to a comment i made that was about a poorly worded doxy
comment. Nicolas has already corrected the doxy and i just wanted to
point out that it appeared to me you misunderstood my comment as
something else.

> 1) We are talking about presentation (display to the user of audio and  
> video.)


> 2) There is a system delay between the call to snd_write_pcm() and when  
> the user actually hears that sound. Assume that this delay is constant,  
> +- half write size.


> 3) This is a (possibly different) system delay between the call to pass  
> video pixels to the video subsystem, and when the user can see that  
> frame of data. Assume this delay is constant, +- half frame.


> Nicolas wants to enable decoders to compensate for the two different  
> system delays. The magnitude of these values is typically in the range  
> 10 - 100 milliseconds.

it can be more but yes

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Many things microsoft did are stupid, but not doing something just because
microsoft did it is even more stupid. If everything ms did were stupid they
would be bankrupt already.
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