[FFmpeg-devel] [PATCH 1/5] libavdevice/avfoundation.m: use setAudioSettings, extend supported formats

[Romain Beauxis]

Le mer. 19 janv. 2022 à 09:45, Gyan Doshi <ffmpeg at gyani.pro> a écrit :
> On 2022-01-19 08:51 pm, Romain Beauxis wrote:
> > Le mer. 19 janv. 2022 à 09:19, Gyan Doshi <ffmpeg at gyani.pro> a écrit :
> >> On 2022-01-19 08:44 pm, Romain Beauxis wrote:
> >>> Le mer. 19 janv. 2022 à 08:31, Gyan Doshi <ffmpeg at gyani.pro> a écrit :
> >>>> On 2022-01-19 07:53 pm, Romain Beauxis wrote:
> >>>>> This patch switches the logic around audio settings to let the caller drive the format.
> >>>>>
> >>>>> After experimenting with the AudioConverter, we realized that, even when adhering to a strict implementation of the documented API, we were still getting errors during conversions. The input device would randomly change from e.g. s32le to s24le between restarts and error out on conversion (using a freshly initialized converter).
> >>>>     At present, the code uses the first frame to set attributes. If you
> >>>> wait for a few frames and then probe, the attributes are stable.
> >>> How is that supposed to work to get a full A/V stream? Discarding
> >>> initial audio frames results in data loss in audio-only input and
> >>> corrupted initial audio in A/V inputs.
> >> We're talking about around 5-6 packets, so ~100 ms. The streaming
> >> scenarios I worked on weren't sensitive to that amount of initial loss.
> >> YMMV.
> > I see thanks. And what advantages does this method provide aside from
> > supporting 24 bit sample formats which are currently excluded from
> > these changes?
>
> I was remarking on a way to avoid format changes post-initialization.
> Not a comment on your patches.

For sure, and I appreciate the feedback.