[FFmpeg-devel] [PATCH 2/2] avformat/matroskaenc: write updated STREAMINFO metadata for FLAC streams if available

[James Almer]

FLAC streams originating from the FLAC encoder send updated and more
complete STREAMINFO metadata as part of the last packet, so write that
to CodecPrivate instead of the incomplete one available in extradata
during init.

Signed-off-by: James Almer <jamrial at gmail.com>
---
 libavformat/matroskaenc.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index f41aabe..8a6a57d 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -130,6 +130,7 @@ typedef struct MatroskaMuxContext {
     int64_t         cluster_pts;
     int64_t         duration_offset;
     int64_t         duration;
+    int64_t         codecpriv_offset;
     mkv_seekhead    *main_seekhead;
     mkv_cues        *cues;
     mkv_track       *tracks;
@@ -1253,6 +1254,7 @@ static int mkv_write_track(AVFormatContext *s, MatroskaMuxContext *mkv,
     }
 
     if (mkv->mode != MODE_WEBM || par->codec_id != AV_CODEC_ID_WEBVTT) {
+        mkv->codecpriv_offset = avio_tell(pb);
         ret = mkv_write_codecprivate(s, pb, par, native_id, qt_id);
         if (ret < 0)
             return ret;
@@ -2078,6 +2080,49 @@ static void mkv_start_new_cluster(AVFormatContext *s, AVPacket *pkt)
     avio_flush(s->pb);
 }
 
+static int mkv_check_new_extra_data(AVFormatContext *s, AVPacket *pkt)
+{
+    MatroskaMuxContext *mkv = s->priv_data;
+    AVCodecParameters *par  = s->streams[pkt->stream_index]->codecpar;
+    uint8_t *side_data;
+    int side_data_size = 0, ret;
+
+    side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
+                                                     &side_data_size);
+
+    switch (par->codec_id) {
+    case AV_CODEC_ID_FLAC:
+        if (side_data_size && s->pb->seekable) {
+            AVCodecParameters *codecpriv_par;
+            int64_t curpos;
+            if (side_data_size != par->extradata_size) {
+                av_log(s, AV_LOG_ERROR, "Invalid FLAC STREAMINFO metadata for output stream %d\n",
+                       pkt->stream_index);
+                return AVERROR(EINVAL);
+            }
+            codecpriv_par = avcodec_parameters_alloc();
+            if (!codecpriv_par)
+                return AVERROR(ENOMEM);
+            ret = avcodec_parameters_copy(codecpriv_par, par);
+            if (ret < 0)
+                return ret;
+            memcpy(codecpriv_par->extradata, side_data, side_data_size);
+            curpos = avio_tell(mkv->tracks_bc);
+            avio_seek(mkv->tracks_bc, mkv->codecpriv_offset, SEEK_SET);
+            mkv_write_codecprivate(s, mkv->tracks_bc, codecpriv_par, 1, 0);
+            avio_seek(mkv->tracks_bc, curpos, SEEK_SET);
+            avcodec_parameters_free(&codecpriv_par);
+        }
+        break;
+    default:
+        if (side_data_size)
+            av_log(s, AV_LOG_DEBUG, "Ignoring new extradata in a packet for stream %d.\n", pkt->stream_index);
+        break;
+    }
+
+    return 0;
+}
+
 static int mkv_write_packet_internal(AVFormatContext *s, AVPacket *pkt, int add_cue)
 {
     MatroskaMuxContext *mkv = s->priv_data;
@@ -2170,6 +2215,10 @@ static int mkv_write_packet(AVFormatContext *s, AVPacket *pkt)
     int ret;
     int start_new_cluster;
 
+    ret = mkv_check_new_extra_data(s, pkt);
+    if (ret < 0)
+        return ret;
+
     if (mkv->tracks[pkt->stream_index].write_dts)
         cluster_time = pkt->dts - mkv->cluster_pts;
     else
-- 
2.10.1