demux_lavf: add a hack to work around other hacks

mplayer (and all forks) use a single FourCC field to map codecs. This is
what sh_video->format and sh_audio->format is used for. Basically it's a
key into the codecs.conf table to find out what decoder to use. (There's
only one video codec and one major audio codec left - both libavcodec.
But we still have to deal with mapping coming from non-libavformat
demuxers.)

It seems this causes some video codecs to fail, such as WV1F in AVI [1].
demux_lavf generally throws away the codec_tag from libavformat if the
codec is MPEG-in-AVI. There are probably other cases like this. Add a
hack to enforce passing the correct codec tag when only ffmpeg demuxers
and decoders involved.

Note: the sample [1] needs to be flipped. With --demuxer=avi, this is
done correctly, because unlike demux_lavf, the demuxer uses the FourCC
directly for the sh_video->format tag, and finds the correct codecs.conf
entry (which contains the flip flag). We could just add a "whitelist" of
codec tags which can be passed through to sh_video->format, but I don't
want to do that just for such an obscure format as the sample at hand.

Note 2: when demux_lavf is used, the AVCodecContext could be passed
directly to vd_ffmpeg/ad_ffmpeg. The code to convert to/from the
internal mplayer stream headers is probably still needed, as there are
non-ffmpeg demuxers and audio decoders.

[1] http://samples.mplayerhq.hu/V-codecs/WV1F/AVI/title2.avi

2 files changed, 4 insertions, 0 deletions

diff --git a/libmpcodecs/ad_ffmpeg.c b/libmpcodecs/ad_ffmpeg.c
index cca7725490..1d6683672b 100644
--- a/libmpcodecs/ad_ffmpeg.c
+++ b/libmpcodecs/ad_ffmpeg.c
@@ -159,6 +159,8 @@ static int init(sh_audio_t *sh_audio)
     }
     lavc_context->request_channels = opts->audio_output_channels;
     lavc_context->codec_tag = sh_audio->format; //FOURCC
+    if (sh_audio->gsh->lavf_codec_tag)
+        lavc_context->codec_tag = sh_audio->gsh->lavf_codec_tag;
     lavc_context->codec_type = AVMEDIA_TYPE_AUDIO;
     lavc_context->codec_id = lavc_codec->id; // not sure if required, imho not --A'rpi
 
diff --git a/libmpcodecs/vd_ffmpeg.c b/libmpcodecs/vd_ffmpeg.c
index 948fde2d00..10d494e48c 100644
--- a/libmpcodecs/vd_ffmpeg.c
+++ b/libmpcodecs/vd_ffmpeg.c
@@ -239,6 +239,8 @@ static int init(sh_video_t *sh)
     } else {
         avctx->pix_fmt = rawfmt;
     }
+    if (sh->gsh->lavf_codec_tag)
+        avctx->codec_tag = sh->gsh->lavf_codec_tag;
     avctx->stream_codec_tag = sh->video.fccHandler;
     avctx->idct_algo = lavc_param->idct_algo;
     avctx->error_concealment = lavc_param->error_concealment;