avformat/mov: add VP8 codec support

Demuxing only. Muxing is disabled as altref frame handling is not
defined in the spec, and there's no way to know the presence of
such frames during stream initialization.

Based on a patch by Steven Liu.

Fixes ticket #7000

Reviewed-by: Carl Eugen Hoyos <ceffmpeg@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/isom.c

@@ -186,6 +186,7 @@ const AVCodecTag ff_codec_movvideo_tags[] = {
     { AV_CODEC_ID_H264, MKTAG('x', 'a', 'l', 'g') }, /* XAVC-L HD422 produced by FCP */
     { AV_CODEC_ID_H264, MKTAG('a', 'v', 'l', 'g') }, /* Panasonic P2 AVC-LongG */
 
+    { AV_CODEC_ID_VP8,  MKTAG('v', 'p', '0', '8') }, /* VP8 */
     { AV_CODEC_ID_VP9,  MKTAG('v', 'p', '0', '9') }, /* VP9 */
 
     { AV_CODEC_ID_MPEG1VIDEO, MKTAG('m', '1', 'v', ' ') },

libavformat/mov.c

@@ -2397,6 +2397,7 @@ static int mov_finalize_stsd_codec(MOVContext *c, AVIOContext *pb,
     case AV_CODEC_ID_EAC3:
     case AV_CODEC_ID_MPEG1VIDEO:
     case AV_CODEC_ID_VC1:
+    case AV_CODEC_ID_VP8:
     case AV_CODEC_ID_VP9:
         st->need_parsing = AVSTREAM_PARSE_FULL;
         break;

libavformat/movenc.c

@@ -6079,6 +6079,11 @@ static int mov_init(AVFormatContext *s)
                     av_log(s, AV_LOG_ERROR, "VP9 only supported in MP4.\n");
                     return AVERROR(EINVAL);
                 }
+            } else if (track->par->codec_id == AV_CODEC_ID_VP8) {
+                /* altref frames handling is not defined in the spec as of version v1.0,
+                 * so just forbid muxing VP8 streams altogether until a new version does */
+                av_log(s, AV_LOG_ERROR, "VP8 muxing is currently not supported.\n");
+                return AVERROR_PATCHWELCOME;
             }
         } else if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
             track->timescale = st->codecpar->sample_rate;