FFmpeg TC input needed
Issue: Patch: avcodec/s302m: enable non-PCM decoding URL: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp... The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer. Summary: SMPTE ST 302 specifies for carriage of LPCM media in MPEG-TS. SMPTE ST 337 enables this for non-PCM codecs. The payload has a custom layout so it can't be directly processed hence lavc/s302m decodes the packet data to yield LPCM media. But it can only deal at present with LPCM payloads, meaning that non-PCM payloads need to be exported to a raw bytestream format and then decoded in a 2nd step, which prohibits direct transcoding of live/streaming inputs. This patch corrects the identification process for non-PCM payloads, reformats the payload and then carries out in-place decoding by calling a nested decoder similar to the ftr or imm5 decoders in lavc. In the v1 patch review, Andreas, in response to the proposed doc entry describing the feature capability of multiple or differing payloads in a s302m stream, suggested[1] that s302m should be a bitstream filter instead, but I did not see that as an actionable suggestion as he immediately listed the bsf limitations preventing the possibility. I also had not seen an actual sample of s302m with multiple embedded streams. Kieran also observed[2] that he had not seen such a stream in the wild. So the added features of this patch, wherever they are ultimately located, shall not yield more than one media stream. Anton suggested[3] that the decoder should instead be a demuxer. I saw no other objections to the architecture of the patch. I posted the v2 patch, incorporating some changes suggested by Andreas, 4 days later. This had gone uncommented for over two weeks when I posted a notice stating an intention to push. Anton posted[4] a new objection that "If it dynamically generates nested decoders, then it's not a proper codec in our model". This new objection is not connected to multiple streams but only to a codec 'model' that I don't see described anywhere and which contradicts the implementations of multiple decoders with a nested decoder, including the ftr and imm5 decoders, which are most similar in design to the patched s302m decoder. Anton later on mentioned[5] that nested decoders are "a constant source of issues". However, I didn't find anything on trac reporting an issue with the nested decoders of ftr and imm5 nor anything on ffmpeg-devel-ml or ffmpeg-user-ml. Nothing in their commit history either points to architectural bugs. These decoders have been around for 6 years among themselves. The testing of the patched s302m decoder over the past month by myself, an OTT provider and others shows no issues either. Finally, Anton speculates[6] that the burden of fixes will likely fall upon him. In none of his objections, till the time of writing, did I see specific concerns with the patch. There are some limitations in shifting this decoder wholesale to inside the MPEG-TS demuxer. A s302m stream may contain some non-media payload accompanying non-PCM media i.e. S-ADM metadata. At present, I have neither the samples nor the specification needed in order to locate and extract or parse this metadata. Formatting the payload data inside the demuxer will lead to irrevocable loss of such metadata if present. However, a decoder patch allows simultaneuous output of both a decoded stream alongside a copied stream. The end-user can then do with the raw data whatever they wish. Ultimately, s302m is specified an an elementary stream inside a MPEG-TS container. Its internal handling is better left to a dedicated module like a decoder. A bitstream filter might be a better fit if s302m streams with multiple media payloads ever start appearing - none have, so far - but for single media payloads, a decoder remains the best place. Regards, Gyan [1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320119.html [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320321.html [3]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320258.html [4]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321514.html [5]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321523.html [6]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321539.html
On Sat, 17 Feb 2024, 11:46 Gyan Doshi, <ffmpeg@gyani.pro> wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Additional comments: Dolby E can exist in any PCM container (wav, MP4). S302M just happens to be a tricky one. Whilst s302m multiple substreams I haven't seen, Dolby E streams internally contain multiple programs, often 5.1 and a 2.0 downmix. Strictly speaking you have to handle the case where the Dolby E frame is misaligned and spans two S302M packets which does exist (and there is ambiguity about the PTS). There is a 3x3 matrix of flavours between coded Dolby E and the carriage PCM (16-bit, 20-bit, 24-bit). Kieran
On 2024-02-17 05:31 pm, Kieran Kunhya wrote:
On Sat, 17 Feb 2024, 11:46 Gyan Doshi,<ffmpeg@gyani.pro> wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Additional comments:
Dolby E can exist in any PCM container (wav, MP4). S302M just happens to be a tricky one.
Whilst s302m multiple substreams I haven't seen, Dolby E streams internally contain multiple programs, often 5.1 and a 2.0 downmix.
That is downstream of the Dolby-E decoder and user will have to use a filter like channelsplit to bifurcate those channels irrespective of where the s302m code resides.
There is a 3x3 matrix of flavours between coded Dolby E and the carriage PCM (16-bit, 20-bit, 24-bit).
Have you seen a larger non-PCM word size inside a smaller AES3 word? Regards, Gyan
On Sat, 17 Feb 2024 18:45:57 +0530 Gyan Doshi <ffmpeg@gyani.pro> wrote:
Whilst s302m multiple substreams I haven't seen, Dolby E streams internally contain multiple programs, often 5.1 and a 2.0 downmix.
That is downstream of the Dolby-E decoder and user will have to use a filter like channelsplit to bifurcate those channels irrespective of where the s302m code resides.
Is there metadata in Dolby E that tells you which channels belong together (and what attributes they might have)? Is it always 5.1+2.0, or could you have e.g. four different 2.0 programs encoded into a single S302M/AES3 stream?
On 2024-02-17 07:12 pm, Niklas Haas wrote:
On Sat, 17 Feb 2024 18:45:57 +0530 Gyan Doshi <ffmpeg@gyani.pro> wrote:
Whilst s302m multiple substreams I haven't seen, Dolby E streams internally contain multiple programs, often 5.1 and a 2.0 downmix. That is downstream of the Dolby-E decoder and user will have to use a filter like channelsplit to bifurcate those channels irrespective of where the s302m code resides. Is there metadata in Dolby E that tells you which channels belong together (and what attributes they might have)? Is it always 5.1+2.0, or could you have e.g. four different 2.0 programs encoded into a single S302M/AES3 stream?
Yes, the metadata is program configuration, with 8 max channels and 8 max programs, so 8 mono programs at most. But my samples are all 5.1+2 or 7.1 or 4.0. These will all result in a single decoded stream from the dolby_e decoder. Regards, Gyan
On Sat, 17 Feb 2024 at 13:16, Gyan Doshi <ffmpeg@gyani.pro> wrote:
Whilst s302m multiple substreams I haven't seen, Dolby E streams internally contain multiple programs, often 5.1 and a 2.0 downmix.
That is downstream of the Dolby-E decoder and user will have to use a filter like channelsplit to bifurcate those channels irrespective of where the s302m code resides.
The point is there are several layers of streams that also can change dynamically.
There is a 3x3 matrix of flavours between coded Dolby E and the carriage PCM (16-bit, 20-bit, 24-bit).
Have you seen a larger non-PCM word size inside a smaller AES3 word?
Actually I think that case won't work in the real world, true as the LSBs will be truncated, not passed along. Kieran
On Sat, Feb 17, 2024 at 05:15:43PM +0530, Gyan Doshi wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
[Nested decoder, bsf, demuxer, something else ...] I think the discussion is too much looking at the fine details What we need is TS -> raw samples TS -> TS (lossless) TS -> nonTS (lossless) nonTS -> TS (lossless) raw samples -> TS I think some of the discussed options have problems with lossless non PCM in some intermediate encapsulation in mpeg-TS thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I do not agree with what you have to say, but I'll defend to the death your right to say it. -- Voltaire
Ping. As the TC rules matter has been concluded, this should go ahead. Regards, Gyan On 2024-02-17 05:15 pm, Gyan Doshi wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Summary:
SMPTE ST 302 specifies for carriage of LPCM media in MPEG-TS. SMPTE ST 337 enables this for non-PCM codecs. The payload has a custom layout so it can't be directly processed hence lavc/s302m decodes the packet data to yield LPCM media. But it can only deal at present with LPCM payloads, meaning that non-PCM payloads need to be exported to a raw bytestream format and then decoded in a 2nd step, which prohibits direct transcoding of live/streaming inputs. This patch corrects the identification process for non-PCM payloads, reformats the payload and then carries out in-place decoding by calling a nested decoder similar to the ftr or imm5 decoders in lavc.
In the v1 patch review, Andreas, in response to the proposed doc entry describing the feature capability of multiple or differing payloads in a s302m stream, suggested[1] that s302m should be a bitstream filter instead, but I did not see that as an actionable suggestion as he immediately listed the bsf limitations preventing the possibility. I also had not seen an actual sample of s302m with multiple embedded streams. Kieran also observed[2] that he had not seen such a stream in the wild. So the added features of this patch, wherever they are ultimately located, shall not yield more than one media stream. Anton suggested[3] that the decoder should instead be a demuxer. I saw no other objections to the architecture of the patch.
I posted the v2 patch, incorporating some changes suggested by Andreas, 4 days later. This had gone uncommented for over two weeks when I posted a notice stating an intention to push. Anton posted[4] a new objection that "If it dynamically generates nested decoders, then it's not a proper codec in our model". This new objection is not connected to multiple streams but only to a codec 'model' that I don't see described anywhere and which contradicts the implementations of multiple decoders with a nested decoder, including the ftr and imm5 decoders, which are most similar in design to the patched s302m decoder. Anton later on mentioned[5] that nested decoders are "a constant source of issues". However, I didn't find anything on trac reporting an issue with the nested decoders of ftr and imm5 nor anything on ffmpeg-devel-ml or ffmpeg-user-ml. Nothing in their commit history either points to architectural bugs. These decoders have been around for 6 years among themselves. The testing of the patched s302m decoder over the past month by myself, an OTT provider and others shows no issues either. Finally, Anton speculates[6] that the burden of fixes will likely fall upon him. In none of his objections, till the time of writing, did I see specific concerns with the patch.
There are some limitations in shifting this decoder wholesale to inside the MPEG-TS demuxer. A s302m stream may contain some non-media payload accompanying non-PCM media i.e. S-ADM metadata. At present, I have neither the samples nor the specification needed in order to locate and extract or parse this metadata. Formatting the payload data inside the demuxer will lead to irrevocable loss of such metadata if present. However, a decoder patch allows simultaneuous output of both a decoded stream alongside a copied stream. The end-user can then do with the raw data whatever they wish.
Ultimately, s302m is specified an an elementary stream inside a MPEG-TS container. Its internal handling is better left to a dedicated module like a decoder. A bitstream filter might be a better fit if s302m streams with multiple media payloads ever start appearing - none have, so far - but for single media payloads, a decoder remains the best place.
Regards, Gyan
[1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320119.html [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320321.html [3]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320258.html [4]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321514.html [5]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321523.html [6]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321539.html
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Ping x2. On 2024-04-02 10:55 am, Gyan Doshi wrote:
Ping.
As the TC rules matter has been concluded, this should go ahead.
Regards, Gyan
On 2024-02-17 05:15 pm, Gyan Doshi wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Summary:
SMPTE ST 302 specifies for carriage of LPCM media in MPEG-TS. SMPTE ST 337 enables this for non-PCM codecs. The payload has a custom layout so it can't be directly processed hence lavc/s302m decodes the packet data to yield LPCM media. But it can only deal at present with LPCM payloads, meaning that non-PCM payloads need to be exported to a raw bytestream format and then decoded in a 2nd step, which prohibits direct transcoding of live/streaming inputs. This patch corrects the identification process for non-PCM payloads, reformats the payload and then carries out in-place decoding by calling a nested decoder similar to the ftr or imm5 decoders in lavc.
In the v1 patch review, Andreas, in response to the proposed doc entry describing the feature capability of multiple or differing payloads in a s302m stream, suggested[1] that s302m should be a bitstream filter instead, but I did not see that as an actionable suggestion as he immediately listed the bsf limitations preventing the possibility. I also had not seen an actual sample of s302m with multiple embedded streams. Kieran also observed[2] that he had not seen such a stream in the wild. So the added features of this patch, wherever they are ultimately located, shall not yield more than one media stream. Anton suggested[3] that the decoder should instead be a demuxer. I saw no other objections to the architecture of the patch.
I posted the v2 patch, incorporating some changes suggested by Andreas, 4 days later. This had gone uncommented for over two weeks when I posted a notice stating an intention to push. Anton posted[4] a new objection that "If it dynamically generates nested decoders, then it's not a proper codec in our model". This new objection is not connected to multiple streams but only to a codec 'model' that I don't see described anywhere and which contradicts the implementations of multiple decoders with a nested decoder, including the ftr and imm5 decoders, which are most similar in design to the patched s302m decoder. Anton later on mentioned[5] that nested decoders are "a constant source of issues". However, I didn't find anything on trac reporting an issue with the nested decoders of ftr and imm5 nor anything on ffmpeg-devel-ml or ffmpeg-user-ml. Nothing in their commit history either points to architectural bugs. These decoders have been around for 6 years among themselves. The testing of the patched s302m decoder over the past month by myself, an OTT provider and others shows no issues either. Finally, Anton speculates[6] that the burden of fixes will likely fall upon him. In none of his objections, till the time of writing, did I see specific concerns with the patch.
There are some limitations in shifting this decoder wholesale to inside the MPEG-TS demuxer. A s302m stream may contain some non-media payload accompanying non-PCM media i.e. S-ADM metadata. At present, I have neither the samples nor the specification needed in order to locate and extract or parse this metadata. Formatting the payload data inside the demuxer will lead to irrevocable loss of such metadata if present. However, a decoder patch allows simultaneuous output of both a decoded stream alongside a copied stream. The end-user can then do with the raw data whatever they wish.
Ultimately, s302m is specified an an elementary stream inside a MPEG-TS container. Its internal handling is better left to a dedicated module like a decoder. A bitstream filter might be a better fit if s302m streams with multiple media payloads ever start appearing - none have, so far - but for single media payloads, a decoder remains the best place.
Regards, Gyan
[1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320119.html [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320321.html [3]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320258.html [4]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321514.html [5]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321523.html [6]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321539.html
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How dare you to question LibAV overlords decisions here! On Mon, Apr 8, 2024 at 3:12 PM Gyan Doshi <ffmpeg@gyani.pro> wrote:
Ping x2.
On 2024-04-02 10:55 am, Gyan Doshi wrote:
Ping.
As the TC rules matter has been concluded, this should go ahead.
Regards, Gyan
On 2024-02-17 05:15 pm, Gyan Doshi wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Summary:
SMPTE ST 302 specifies for carriage of LPCM media in MPEG-TS. SMPTE ST 337 enables this for non-PCM codecs. The payload has a custom layout so it can't be directly processed hence lavc/s302m decodes the packet data to yield LPCM media. But it can only deal at present with LPCM payloads, meaning that non-PCM payloads need to be exported to a raw bytestream format and then decoded in a 2nd step, which prohibits direct transcoding of live/streaming inputs. This patch corrects the identification process for non-PCM payloads, reformats the payload and then carries out in-place decoding by calling a nested decoder similar to the ftr or imm5 decoders in lavc.
In the v1 patch review, Andreas, in response to the proposed doc entry describing the feature capability of multiple or differing payloads in a s302m stream, suggested[1] that s302m should be a bitstream filter instead, but I did not see that as an actionable suggestion as he immediately listed the bsf limitations preventing the possibility. I also had not seen an actual sample of s302m with multiple embedded streams. Kieran also observed[2] that he had not seen such a stream in the wild. So the added features of this patch, wherever they are ultimately located, shall not yield more than one media stream. Anton suggested[3] that the decoder should instead be a demuxer. I saw no other objections to the architecture of the patch.
I posted the v2 patch, incorporating some changes suggested by Andreas, 4 days later. This had gone uncommented for over two weeks when I posted a notice stating an intention to push. Anton posted[4] a new objection that "If it dynamically generates nested decoders, then it's not a proper codec in our model". This new objection is not connected to multiple streams but only to a codec 'model' that I don't see described anywhere and which contradicts the implementations of multiple decoders with a nested decoder, including the ftr and imm5 decoders, which are most similar in design to the patched s302m decoder. Anton later on mentioned[5] that nested decoders are "a constant source of issues". However, I didn't find anything on trac reporting an issue with the nested decoders of ftr and imm5 nor anything on ffmpeg-devel-ml or ffmpeg-user-ml. Nothing in their commit history either points to architectural bugs. These decoders have been around for 6 years among themselves. The testing of the patched s302m decoder over the past month by myself, an OTT provider and others shows no issues either. Finally, Anton speculates[6] that the burden of fixes will likely fall upon him. In none of his objections, till the time of writing, did I see specific concerns with the patch.
There are some limitations in shifting this decoder wholesale to inside the MPEG-TS demuxer. A s302m stream may contain some non-media payload accompanying non-PCM media i.e. S-ADM metadata. At present, I have neither the samples nor the specification needed in order to locate and extract or parse this metadata. Formatting the payload data inside the demuxer will lead to irrevocable loss of such metadata if present. However, a decoder patch allows simultaneuous output of both a decoded stream alongside a copied stream. The end-user can then do with the raw data whatever they wish.
Ultimately, s302m is specified an an elementary stream inside a MPEG-TS container. Its internal handling is better left to a dedicated module like a decoder. A bitstream filter might be a better fit if s302m streams with multiple media payloads ever start appearing - none have, so far - but for single media payloads, a decoder remains the best place.
Regards, Gyan
[1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320119.html [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320321.html [3]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320258.html [4]:
https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321514.html
[5]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321523.html [6]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321539.html
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On Sat, 17 Feb 2024 17:15:43 +0530 Gyan Doshi <ffmpeg@gyani.pro> wrote:
Issue:
Patch: avcodec/s302m: enable non-PCM decoding URL: https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp...
The issue needing resolution is whether the patch should be added to the existing s302m decoder or should that decoder be removed and all old and new patched features inlined into the mpeg-ts demuxer.
Summary:
SMPTE ST 302 specifies for carriage of LPCM media in MPEG-TS. SMPTE ST 337 enables this for non-PCM codecs. The payload has a custom layout so it can't be directly processed hence lavc/s302m decodes the packet data to yield LPCM media. But it can only deal at present with LPCM payloads, meaning that non-PCM payloads need to be exported to a raw bytestream format and then decoded in a 2nd step, which prohibits direct transcoding of live/streaming inputs. This patch corrects the identification process for non-PCM payloads, reformats the payload and then carries out in-place decoding by calling a nested decoder similar to the ftr or imm5 decoders in lavc.
In the v1 patch review, Andreas, in response to the proposed doc entry describing the feature capability of multiple or differing payloads in a s302m stream, suggested[1] that s302m should be a bitstream filter instead, but I did not see that as an actionable suggestion as he immediately listed the bsf limitations preventing the possibility. I also had not seen an actual sample of s302m with multiple embedded streams. Kieran also observed[2] that he had not seen such a stream in the wild. So the added features of this patch, wherever they are ultimately located, shall not yield more than one media stream. Anton suggested[3] that the decoder should instead be a demuxer. I saw no other objections to the architecture of the patch.
I posted the v2 patch, incorporating some changes suggested by Andreas, 4 days later. This had gone uncommented for over two weeks when I posted a notice stating an intention to push. Anton posted[4] a new objection that "If it dynamically generates nested decoders, then it's not a proper codec in our model". This new objection is not connected to multiple streams but only to a codec 'model' that I don't see described anywhere and which contradicts the implementations of multiple decoders with a nested decoder, including the ftr and imm5 decoders, which are most similar in design to the patched s302m decoder. Anton later on mentioned[5] that nested decoders are "a constant source of issues". However, I didn't find anything on trac reporting an issue with the nested decoders of ftr and imm5 nor anything on ffmpeg-devel-ml or ffmpeg-user-ml. Nothing in their commit history either points to architectural bugs. These decoders have been around for 6 years among themselves. The testing of the patched s302m decoder over the past month by myself, an OTT provider and others shows no issues either. Finally, Anton speculates[6] that the burden of fixes will likely fall upon him. In none of his objections, till the time of writing, did I see specific concerns with the patch.
There are some limitations in shifting this decoder wholesale to inside the MPEG-TS demuxer. A s302m stream may contain some non-media payload accompanying non-PCM media i.e. S-ADM metadata. At present, I have neither the samples nor the specification needed in order to locate and extract or parse this metadata. Formatting the payload data inside the demuxer will lead to irrevocable loss of such metadata if present. However, a decoder patch allows simultaneuous output of both a decoded stream alongside a copied stream. The end-user can then do with the raw data whatever they wish.
Ultimately, s302m is specified an an elementary stream inside a MPEG-TS container. Its internal handling is better left to a dedicated module like a decoder. A bitstream filter might be a better fit if s302m streams with multiple media payloads ever start appearing - none have, so far - but for single media payloads, a decoder remains the best place.
Regards, Gyan
[1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320119.html [2]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320321.html [3]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-January/320258.html [4]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321514.html [5]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321523.html [6]: https://ffmpeg.org/pipermail/ffmpeg-devel/2024-February/321539.html
Hi, This is in regards to the patch "avcodec/s302m: enable non-PCM decoding" by Gyan Doshi. https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240127103854.9971-1-ffmp... The TC has voted on the matter, with all 5 voting members unanimously voting against the patch. The opposition to the patch was based on the opinion that this implementation of S302M should be handled by libavformat, not libavcodec. The central argument focused on the ways in which these formats can interact. In particular, S302M is always tied to MPEG-TS, but Dolby E can also exist in other containers, so exposing Dolby E as the the intermediary (AV_CODEC_ID) unlocks the full range of possible operations (e.g. S302M -> Dolby E -> MXF remux). Regarding Gyan Doshi's main objection that doing so would possibly delete S302M metadata (e.g. S-ADM), it was observed that if the need for such metadata truly arises, it should either be parsed by FFmpeg or attached as an opaque side data blob (only if the former is impossible). Therefore, the matter has been decided, rejecting the patch at hand. Regards, The FFmpeg Technical Committee - Jan Ekström - Niklas Haas - Anton Khirnov - Michael Niedermayer - Martin Storsjö - Mark Thompson
participants (5)
-
Gyan Doshi -
Kieran Kunhya -
Michael Niedermayer -
Niklas Haas -
Paul B Mahol