On Fri, Feb 12, 2021 at 12:36 PM Matthieu Bouron
<matthieu.bou...@gmail.com> wrote:
>
> On Mon, Jan 25, 2021 at 06:38:36PM +0100, sfan5 wrote:
> > Although rare, extradata can be present but empty and extraction will fail.
> > However Android also supports passing codec-specific data inline and
> > will likely play such a stream anyway. So there's no reason to abort
> > initialization before we know for sure.
> > ---
> > libavcodec/mediacodecdec.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/libavcodec/mediacodecdec.c b/libavcodec/mediacodecdec.c
> > index ac1725e466..67adefb530 100644
> > --- a/libavcodec/mediacodecdec.c
> > +++ b/libavcodec/mediacodecdec.c
> > @@ -167,8 +167,8 @@ static int h264_set_extradata(AVCodecContext *avctx,
> > FFAMediaFormat *format)
> > ff_AMediaFormat_setBuffer(format, "csd-1", (void*)data, data_size);
> > av_freep(&data);
> > } else {
> > - av_log(avctx, AV_LOG_ERROR, "Could not extract PPS/SPS from
> > extradata");
> > - ret = AVERROR_INVALIDDATA;
> > + av_log(avctx, AV_LOG_WARNING, "Could not extract PPS/SPS from
> > extradata\n");
> > + ret = 0;
> > }
> > done:
> > @@ -254,8 +254,8 @@ static int hevc_set_extradata(AVCodecContext *avctx,
> > FFAMediaFormat *format)
> > av_freep(&data);
> > } else {
> > - av_log(avctx, AV_LOG_ERROR, "Could not extract VPS/PPS/SPS from
> > extradata");
> > - ret = AVERROR_INVALIDDATA;
> > + av_log(avctx, AV_LOG_WARNING, "Could not extract VPS/PPS/SPS from
> > extradata\n");
> > + ret = 0;
> > }
> > done:
>
> Hello,
>
> First of all, sorry for the late reply. The original intent with this
> restriction was to make sure that MediaCodec could error out early (at the
> configuration stage) so an implementation on top of libavcodec can decide
> to fall back to a software decoder (without trying to decode anything).
>
> I am fine with removing this restriction (if everyone is OK with that) for
> the following reasons:
> - there are chances that the h264/hevc software decoders have not been
> enabled (to avoid licensing issues) so the fallback mechanism is not
> available
> - as you said extradata are not always available (mpegts) and we want to
> give MediaCodec a chance to decode the stream
I just had a discussion with sfan5 on IRC yesterday when I was looking
at the related code, and yea - I think this is acceptable since to get
to this point ff_h264_decode_extradata / ff_hevc_decode_extradata
would have to return success. They just didn't get anything. This can
happen with f.ex. completely valid MP4 files, since certain
identifiers (which are visible through the codec_tag identifier) do
not required all of the required parameter sets to be within the
extradata (and thus having 0 pps and 0 sps is technically valid with
those).
My idea was thus to make the log message either WARNING or DEBUG
depending on (is_avc || is_nalff) && codec_tag in (list, of, tags) (in
pseudocode). How matroska should be handled depends on how the codec
stuff is currently defined in there.
>
> So LGTM.
>
> If everyone is OK with that, I'll also submit a patch that removes the
> requirements on having the avctx->extradata set (I use such patch at work
> to allow playback of certain hls/mpegts streams).
>
> [...]
> --
> Matthieu B.
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