[FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[Romain Beauxis]

This patch makes sure that ogg/flac headers are parsed again when
encountering a new logic stream inside a chained ogg bistream[1].

This patches makes it possible to retrieve metadata in chained ogg/flac
bitstreams. It is particularly important because ogg/flac is one of the
only (if not the only one) lossless container supported over HTTP/icecast.

The patch has been tested with various ogg/flac encoders and appears to
work fine with ffmpeg.

1: https://xiph.org/ogg/doc/oggstream.html

---
 libavformat/oggdec.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 5339fdd32c..d986e19817 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -239,8 +239,11 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, char *magic,
     os->start_trimming = 0;
     os->end_trimming = 0;
 
-    /* Chained files have extradata as a new packet */
-    if (codec == &ff_opus_codec)
+    /* Parse opus and flac header on new chained bitstreams.
+     * For opus, header contains required extradata as new packet.
+     * For both formats, this makes it possible to read chained metadata. */
+    if (codec == &ff_opus_codec ||
+        codec == &ff_flac_codec)
         os->header = -1;
 
     return i;
-- 
2.39.5 (Apple Git-154)

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Re: [FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[Romain Beauxis]

Hi all!

Le sam. 18 janv. 2025 à 11:54, Romain Beauxis
<romain.beauxis@gmail.com> a écrit :
>
> This patch makes sure that ogg/flac headers are parsed again when
> encountering a new logic stream inside a chained ogg bistream[1].
>
> This patches makes it possible to retrieve metadata in chained ogg/flac
> bitstreams. It is particularly important because ogg/flac is one of the
> only (if not the only one) lossless container supported over HTTP/icecast.
>
> The patch has been tested with various ogg/flac encoders and appears to
> work fine with ffmpeg.

Anybody interested in reviewing/testing the patch? Happy to provide
some streams or you can literally concatenate two ogg/flac files
together.

I know for a fact that it would be very useful to people using ffmpeg
either directly or through its libraries.

Thanks,
-- Romain

> 1: https://xiph.org/ogg/doc/oggstream.html
>
> ---
>  libavformat/oggdec.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
> index 5339fdd32c..d986e19817 100644
> --- a/libavformat/oggdec.c
> +++ b/libavformat/oggdec.c
> @@ -239,8 +239,11 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, char *magic,
>      os->start_trimming = 0;
>      os->end_trimming = 0;
>
> -    /* Chained files have extradata as a new packet */
> -    if (codec == &ff_opus_codec)
> +    /* Parse opus and flac header on new chained bitstreams.
> +     * For opus, header contains required extradata as new packet.
> +     * For both formats, this makes it possible to read chained metadata. */
> +    if (codec == &ff_opus_codec ||
> +        codec == &ff_flac_codec)
>          os->header = -1;
>
>      return i;
> --
> 2.39.5 (Apple Git-154)
>
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Re: [FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 1325 bytes --]

On Fri, Jan 24, 2025 at 07:40:40PM -0600, Romain Beauxis wrote:
> Hi all!
> 
> Le sam. 18 janv. 2025 à 11:54, Romain Beauxis
> <romain.beauxis@gmail.com> a écrit :
> >
> > This patch makes sure that ogg/flac headers are parsed again when
> > encountering a new logic stream inside a chained ogg bistream[1].
> >
> > This patches makes it possible to retrieve metadata in chained ogg/flac
> > bitstreams. It is particularly important because ogg/flac is one of the
> > only (if not the only one) lossless container supported over HTTP/icecast.
> >
> > The patch has been tested with various ogg/flac encoders and appears to
> > work fine with ffmpeg.
> 
> Anybody interested in reviewing/testing the patch? Happy to provide
> some streams or you can literally concatenate two ogg/flac files
> together.
> 
> I know for a fact that it would be very useful to people using ffmpeg
> either directly or through its libraries.

maybe you can add a fate test with a small or generated sample

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]

[-- Attachment #2: Type: text/plain, Size: 251 bytes --]

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Re: [FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[Romain Beauxis]

Le mar. 28 janv. 2025 à 00:25, Michael Niedermayer
<michael@niedermayer.cc> a écrit :
>
> On Fri, Jan 24, 2025 at 07:40:40PM -0600, Romain Beauxis wrote:
> > Hi all!
> >
> > Le sam. 18 janv. 2025 à 11:54, Romain Beauxis
> > <romain.beauxis@gmail.com> a écrit :
> > >
> > > This patch makes sure that ogg/flac headers are parsed again when
> > > encountering a new logic stream inside a chained ogg bistream[1].
> > >
> > > This patches makes it possible to retrieve metadata in chained ogg/flac
> > > bitstreams. It is particularly important because ogg/flac is one of the
> > > only (if not the only one) lossless container supported over HTTP/icecast.
> > >
> > > The patch has been tested with various ogg/flac encoders and appears to
> > > work fine with ffmpeg.
> >
> > Anybody interested in reviewing/testing the patch? Happy to provide
> > some streams or you can literally concatenate two ogg/flac files
> > together.
> >
> > I know for a fact that it would be very useful to people using ffmpeg
> > either directly or through its libraries.
>
> maybe you can add a fate test with a small or generated sample

Yes!

Took a little more work because you need to dump it from the AVStream
but I got a test program ready and hooked up for it, will send an
updated patch right now.

-- Romain
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