[FFmpeg-devel] Swresample strangeness

[Marton Balint]

On Sun, 25 Feb 2024, Michael Niedermayer wrote:

> On Sun, Feb 25, 2024 at 05:38:27PM +0100, Marton Balint wrote:
>> Hi,
>>
>> I am working on a patch to select a better default packet size for the wav
>> demuxer, since it reads at most 4096 bytes which can cause insanely small
>> packets for files with high channel count.
>>
>> Unfortunately some swresample fate tests blew up, and I wonder if the result
>> of the resampling should be dependant on size of the audio chunks which are
>> being fed to it. My assumption is that if it causes audible difference in
>> the output, then it is likely a bug in swresample, but I am not familiar
>> with its code and its many tunable variables, so if someone could confirm,
>> (or even better, fix it :)) that would be great.
>
> From what you describe, the first thing that comes to mind are timestamps.
> If you resample with timestamps that mismatch the exact values expected from
> the sample rate. You will have different resuls when the packet size is changed.
> Its the same data but at a different point in time and thats different then.
>
> I have too many things to do though so i cant really look into this.

Ok, thanks anyway. For the async tests the timestamps were randomly 
generated, and that changed. For other tests however I am quite 
sure about the swresample bug, so I will send a patch soon to fix that.

Regards,
Marton