[FFmpeg-devel] [PATCH] avformat/movenc: Fix writing a sample size of 0 for PCM in MP4

[Raphaël Zumer]

Encoding PCM in MP4 currently causes subsequent decoding to fail due to a sample size of 0.

Use bits per coded sample instead, which are set correctly based on my tests and allow muxed files to be decoded as expected.

Note: PCM in MP4 muxed with versions of FFmpeg 6.0 and prior (before implementation of the pcmC box) will continue to fail decoding due to the sample size not being available. I see that it was assumed to be 16-bit before commit d4ee17.

Signed-off-by: Raphaël Zumer <rzumer at tebako.net>
---
  libavformat/movenc.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index f1cc80b1b3..3c44ace5b0 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1237,7 +1237,7 @@ static int mov_write_pcmc_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
                      track->par->codec_id == AV_CODEC_ID_PCM_S24LE ||
                      track->par->codec_id == AV_CODEC_ID_PCM_S32LE);
      avio_w8(pb, format_flags);
-    avio_w8(pb, track->par->bits_per_raw_sample);
+    avio_w8(pb, track->par->bits_per_coded_sample);
  
      return update_size(pb, pos);
  }
-- 
2.41.0