matroska: implement support for ProRes

Support Matroska native formatting.

On demuxing prepend a Frame container atom (32bit big endian encoded
frame size and 'icpf' string).
On muxing remove it.

1 files changed, 10 insertions, 2 deletions

diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 521f6b5c1a..3e32943153 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -1050,7 +1050,7 @@ static void mkv_write_block(AVFormatContext *s, AVIOContext *pb,
     MatroskaMuxContext *mkv = s->priv_data;
     AVCodecContext *codec = s->streams[pkt->stream_index]->codec;
     uint8_t *data = NULL;
-    int size = pkt->size;
+    int offset = 0, size = pkt->size;
     int64_t ts = mkv->tracks[pkt->stream_index].write_dts ? pkt->dts : pkt->pts;
 
     av_log(s, AV_LOG_DEBUG, "Writing block at offset %" PRIu64 ", size %d, "
@@ -1061,12 +1061,20 @@ static void mkv_write_block(AVFormatContext *s, AVIOContext *pb,
         ff_avc_parse_nal_units_buf(pkt->data, &data, &size);
     else
         data = pkt->data;
+
+    if (codec->codec_id == AV_CODEC_ID_PRORES) {
+        /* Matroska specification requires to remove the first QuickTime atom
+         */
+        size -= 8;
+        offset = 8;
+    }
+
     put_ebml_id(pb, blockid);
     put_ebml_num(pb, size+4, 0);
     avio_w8(pb, 0x80 | (pkt->stream_index + 1));     // this assumes stream_index is less than 126
     avio_wb16(pb, ts - mkv->cluster_pts);
     avio_w8(pb, flags);
-    avio_write(pb, data, size);
+    avio_write(pb, data + offset, size);
     if (data != pkt->data)
         av_free(data);
 }