[FFmpeg-devel] [PATCH] avformat/mov: read PCM audio configuration box ('pcmC') if available

[Ivan Baykalov <4rusxg@gmail.com>]

For ipcm and fpcm streams, big-endian format is the default, but it can be changed
with additional 'pcmC' sub-atom of audio sample description.

Details can be found in ISO/IEC 23003-5:2020

Fixes ticket #9763
Fixes ticket #9790
---
 libavformat/mov.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index d7be593a86..f71a470d9c 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -7567,6 +7567,65 @@ static int mov_read_iloc(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return atom.size;
 }
 
+static int mov_read_pcmc(MOVContext *c, AVIOContext *pb, MOVAtom atom)
+{
+    int version, format_flags, pcm_sample_size;
+    AVStream *st;
+
+    if (atom.size < 6) {
+        av_log(c->fc, AV_LOG_ERROR, "Empty pcmC box\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    version = avio_r8(pb);
+    if (version) {
+        av_log(c->fc, AV_LOG_WARNING, "Unsupported pcmC box version %d\n", version);
+        return 0;
+    }
+
+    avio_rb24(pb);  // flags
+
+    if (c->fc->nb_streams < 1)
+        return 0;
+    st = c->fc->streams[c->fc->nb_streams-1];
+    if (!st || !st->codecpar)
+        return 0;
+
+    format_flags = avio_r8(pb);
+    if (format_flags == 1) { // indicates little-endian format. If not present, big-endian format is used
+        if (st->codecpar->codec_tag == MKTAG('i','p','c','m')) {
+            switch (st->codecpar->codec_id) {
+                case AV_CODEC_ID_PCM_S16BE:
+                    st->codecpar->codec_id = AV_CODEC_ID_PCM_S16LE;
+                    break;
+                case AV_CODEC_ID_PCM_S24BE:
+                    st->codecpar->codec_id = AV_CODEC_ID_PCM_S24LE;
+                    break;
+                case AV_CODEC_ID_PCM_S32BE:
+                    st->codecpar->codec_id = AV_CODEC_ID_PCM_S32LE;
+                    break;
+            }
+        }
+        else if (st->codecpar->codec_tag == MKTAG('f','p','c','m')) {
+            switch (st->codecpar->codec_id) {
+                case AV_CODEC_ID_PCM_F32BE:
+                    st->codecpar->codec_id = AV_CODEC_ID_PCM_F32LE;
+                    break;
+                case AV_CODEC_ID_PCM_F64BE:
+                    st->codecpar->codec_id = AV_CODEC_ID_PCM_F64LE;
+                    break;
+            }
+        }
+    }
+
+    pcm_sample_size = avio_r8(pb);
+    if (pcm_sample_size != st->codecpar->bits_per_coded_sample) {
+        av_log(c->fc, AV_LOG_WARNING, "Unexpected pcmC sample size (%d vs %d)\n", pcm_sample_size, st->codecpar->bits_per_coded_sample);
+    }
+
+    return 0;
+}
+
 static const MOVParseTableEntry mov_default_parse_table[] = {
 { MKTAG('A','C','L','R'), mov_read_aclr },
 { MKTAG('A','P','R','G'), mov_read_avid },
@@ -7670,6 +7729,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
 { MKTAG('S','A','3','D'), mov_read_SA3D }, /* ambisonic audio box */
 { MKTAG('S','A','N','D'), mov_read_SAND }, /* non diegetic audio box */
 { MKTAG('i','l','o','c'), mov_read_iloc },
+{ MKTAG('p','c','m','C'), mov_read_pcmc }, /* PCM configuration box */
 { 0, NULL }
 };
 
-- 
2.35.1

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