Quoting Gyan Doshi (2024-01-26 05:23:50) > > > On 2024-01-25 06:47 pm, Andreas Rheinhardt wrote: > > Gyan Doshi: > >> > >> On 2024-01-25 10:29 am, Andreas Rheinhardt wrote: > >>> Gyan Doshi: > >>>> Set up framework for non-PCM decoding in-place and > >>>> add support for Dolby-E decoding. > >>>> > >>>> Useful for direct transcoding of non-PCM audio in live inputs. > >>>> --- > >>>> configure | 1 + > >>>> doc/decoders.texi | 40 +++ > >>>> libavcodec/s302m.c | 609 +++++++++++++++++++++++++++++++++++++-------- > >>>> 3 files changed, 543 insertions(+), 107 deletions(-) > >>>> > >>>> diff --git a/configure b/configure > >>>> index c8ae0a061d..8db3fa3f4b 100755 > >>>> --- a/configure > >>>> +++ b/configure > >>>> @@ -2979,6 +2979,7 @@ rv20_decoder_select="h263_decoder" > >>>> rv20_encoder_select="h263_encoder" > >>>> rv30_decoder_select="golomb h264pred h264qpel mpegvideodec rv34dsp" > >>>> rv40_decoder_select="golomb h264pred h264qpel mpegvideodec rv34dsp" > >>>> +s302m_decoder_select="dolby_e_decoder" > >>>> screenpresso_decoder_deps="zlib" > >>>> shorten_decoder_select="bswapdsp" > >>>> sipr_decoder_select="lsp" > >>>> diff --git a/doc/decoders.texi b/doc/decoders.texi > >>>> index 293c82c2ba..9f85c876bf 100644 > >>>> --- a/doc/decoders.texi > >>>> +++ b/doc/decoders.texi > >>>> @@ -347,6 +347,46 @@ configuration. You need to explicitly configure > >>>> the build with > >>>> An FFmpeg native decoder for Opus exists, so users can decode Opus > >>>> without this library. > >>>> +@section s302m > >>>> + > >>>> +SMPTE ST 302 decoder. > >>>> + > >>>> +SMPTE ST 302 is a method for storing AES3 data format within an MPEG > >>>> Transport > >>>> +Stream. AES3 streams can contain LPCM streams of 2, 4, 6 or 8 > >>>> channels with a > >>>> +bit depth of 16, 20 or 24-bits at a sample rate of 48 kHz. > >>>> +They can also contain non-PCM codec streams such as AC-3 or Dolby-E. > >>>> + > >>> This sounds like we should add bitstream filters to extract the proper > >>> underlying streams instead. > >>> (I see only two problems with this approach: The BSF API needs to set > >>> the CodecID of the output during init, but at this point no packet has > >>> reached the BSF to determine it. And changing codec IDs mid-stream is > >>> also not supported.) > >> In theory, this decoder shouldn't exist, as it is just a carrier, > >> whether of LPCM or non-PCM. > >> FFmpeg architecture also imposes a fundamental limitation in that one > >> s302m stream may > >> carry multiple payload streams and we support only one decoding context > >> per input stream > > Then why does the demuxer not separate the data into multiple streams? > > I didn't add demuxing support for this codec in MPEGTS, but I can venture > > a) it would mean essentially inlining this decoder in the demuxer.
Why is that a problem? This decoder seems like it shouldn't be a decoder. I agree with Andreas that this seems like it's a demuxer pretending to be a decoder. -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
