Re: [FFmpeg-devel] [PATCHv3 7/8] avformat/aiff: G.728 muxing and demuxing

From: Peter Ross <pross@xvid.org>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCHv3 7/8] avformat/aiff: G.728 muxing and demuxing
Date: Tue, 10 Jun 2025 10:29:40 +1000
Message-ID: <aEd8dD3Eara3_95N@6adec48d008b490a866cba579a4e4931> (raw)
In-Reply-To: <GV1P250MB0737B292BE5B0EFE4C64BA4D8F6BA@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM>

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On Tue, Jun 10, 2025 at 12:25:24AM +0200, Andreas Rheinhardt wrote:
> Peter Ross:
> > ---
> >  libavformat/aiff.c    | 1 +
> >  libavformat/aiffdec.c | 3 +++
> >  2 files changed, 4 insertions(+)
> > 
> > diff --git a/libavformat/aiff.c b/libavformat/aiff.c
> > index 1ceac69a70..907f7d8d28 100644
> > --- a/libavformat/aiff.c
> > +++ b/libavformat/aiff.c
> > @@ -40,6 +40,7 @@ const AVCodecTag ff_codec_aiff_tags[] = {
> >      { AV_CODEC_ID_GSM,          MKTAG('G','S','M',' ') },
> >      { AV_CODEC_ID_ADPCM_G722,   MKTAG('G','7','2','2') },
> >      { AV_CODEC_ID_ADPCM_G726LE, MKTAG('G','7','2','6') },
> > +    { AV_CODEC_ID_G728,         MKTAG('G','7','2','8') },
> >      { AV_CODEC_ID_PCM_S16BE,    MKTAG('t','w','o','s') },
> >      { AV_CODEC_ID_PCM_S16LE,    MKTAG('s','o','w','t') },
> >      { AV_CODEC_ID_ADPCM_IMA_QT, MKTAG('i','m','a','4') },
> > diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
> > index bd5bd2e4bb..aeb00cccd0 100644
> > --- a/libavformat/aiffdec.c
> > +++ b/libavformat/aiffdec.c
> > @@ -174,6 +174,9 @@ static int get_aiff_header(AVFormatContext *s, int64_t size,
> >          case AV_CODEC_ID_GSM:
> >              par->block_align = 33;
> >              break;
> > +        case AV_CODEC_ID_G728:
> > +            par->block_align = 5;
> > +            break;
> >          default:
> >              aiff->block_duration = 1;
> >              break;
> > 
> Is this and the riff patch based on some spec or are you just inventing
> things here?

No inventions.

The aiff patch is based on sample here:
https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/AIFF/Samples.html
Search for G.728. I am unsure what software was used to create that sample.

The riff twocc's originate from binary G.728 ACM DLLs:
	kdg728.acm "Kedacom G.728" 0x0041 
	plcmg728.acm "Polycom G.728" 0xCD02

I have tested remuxing raw G.728 into riff wav using ffmpeg, and playing them
back on windows using the ACM DLLs.

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)

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