[FFmpeg-devel] [PATCH v2 7/8] avformat/movenc: write ChannelLayout box for PCM

[Zhao Zhili]

From: Zhao Zhili <zhilizhao at tencent.com>

Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>
---
 libavformat/movenc.c | 48 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 1 deletion(-)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 3315057b88..058d3cd6d1 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1199,6 +1199,47 @@ static int is_mp4_pcm_codec(enum AVCodecID codec)
     }
 }
 
+static int mov_write_chnl_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
+{
+    int64_t pos = avio_tell(pb);
+    int config = 0;
+    int ret;
+    uint8_t *speaker_pos = NULL;
+    const AVChannelLayout *layout = &track->par->ch_layout;
+
+    ret = ff_mov_get_channel_config_from_layout(layout, &config);
+    if (ret || !config) {
+        config = 0;
+        speaker_pos = av_malloc(layout->nb_channels);
+        ret = ff_mov_get_channel_positions_from_layout(layout,
+                speaker_pos, layout->nb_channels);
+        if (ret) {
+            char buf[128] = {};
+
+            av_freep(&speaker_pos);
+            av_channel_layout_describe(layout, buf, sizeof(buf));
+            av_log(s, AV_LOG_ERROR, "unsupported channel layout %s\n", buf);
+            return ret;
+        }
+    }
+
+    avio_wb32(pb, 0); /* size */
+    ffio_wfourcc(pb, "chnl");
+    avio_wb32(pb, 0); /* version & flags */
+
+    avio_w8(pb, 1); /* stream_structure */
+    avio_w8(pb, config);
+    if (config) {
+        avio_wb64(pb, 0);
+    } else {
+        for (int i = 0; i < layout->nb_channels; i++)
+            avio_w8(pb, speaker_pos[i]);
+        av_freep(&speaker_pos);
+    }
+
+    return update_size(pb, pos);
+}
+
 static int mov_write_pcmc_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
 {
     int64_t pos = avio_tell(pb);
@@ -1349,8 +1390,13 @@ static int mov_write_audio_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContex
         ret = mov_write_dmlp_tag(s, pb, track);
     else if (track->vos_len > 0)
         ret = mov_write_glbl_tag(pb, track);
-    else if (track->mode == MODE_MP4 && is_mp4_pcm_codec(track->par->codec_id))
+    else if (track->mode == MODE_MP4 && is_mp4_pcm_codec(track->par->codec_id)) {
+        if (track->par->ch_layout.nb_channels > 1)
+            ret = mov_write_chnl_tag(s, pb, track);
+        if (ret < 0)
+            return ret;
         ret = mov_write_pcmc_tag(s, pb, track);
+    }
 
     if (ret < 0)
         return ret;
-- 
2.34.1