On Sat, Aug 30, 2025 at 04:27:25PM -0700, Spencer Alves via ffmpeg-devel wrote:
> The 'smpl' chunk is used for sampling music synthesizers, and includes
> things like the pitch of the sample and how to loop it. This exposes the
> loop points as "loop_start" and "loop_end" metadata, that the brstm, mca,
> and scd demuxers already support.
>
> Tested with file output from "Polyphone" soundfont editor.
>
> Signed-off-by: Spencer Alves <impi...@gmail.com>
> ---
> libavformat/wavdec.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/libavformat/wavdec.c b/libavformat/wavdec.c
> index c65e0a2723..fb3749d64d 100644
> --- a/libavformat/wavdec.c
> +++ b/libavformat/wavdec.c
> @@ -595,6 +595,28 @@ static int wav_read_header(AVFormatContext *s)
> }
> }
> break;
> + case MKTAG('s', 'm', 'p', 'l'):
> + if (size >= 36 && got_fmt && st->codecpar->sample_rate > 0) {
> + unsigned sample_loop_count;
> + avio_skip(pb, 28);
> + sample_loop_count = avio_rl32(pb);
> + avio_skip(pb, 4);
> + for (unsigned i = 0; i < sample_loop_count; i++) {
> + avio_skip(pb, 8);
> + if (av_dict_set_int(&s->metadata, "loop_start",
> + av_rescale(avio_rl32(pb), AV_TIME_BASE,
> + st->codecpar->sample_rate),
> + AV_DICT_MULTIKEY) < 0)
> + return AVERROR(ENOMEM);
> + avio_skip(pb, 8);
> + if (av_dict_set_int(&s->metadata, "loop_end",
> + av_rescale(avio_rl32(pb), AV_TIME_BASE,
> + st->codecpar->sample_rate),
> + AV_DICT_MULTIKEY) < 0)
> + return AVERROR(ENOMEM);
> + }
> + }
> + break;
> }
> /* seek to next tag unless we know that we'll run into EOF */
> -- error: corrupt patch at line 38 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Opposition brings concord. Out of discord comes the fairest harmony. -- Heraclitus
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list -- ffmpeg-devel@ffmpeg.org To unsubscribe send an email to ffmpeg-devel-le...@ffmpeg.org
