On Thu, Nov 10, 2011 at 11:19:30AM -0500, Justin Ruggles wrote:
> On 11/10/2011 10:56 AM, Kostya Shishkov wrote:
>
> > On Thu, Nov 10, 2011 at 10:44:55AM -0500, Justin Ruggles wrote:
> >> The Musepack SV7 reference encoder converts mono to stereo when encoding.
> >> ---
> >> libavcodec/mpc7.c | 9 ++++++++-
> >> 1 files changed, 8 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/libavcodec/mpc7.c b/libavcodec/mpc7.c
> >> index 6f79c7b..fea60a1 100644
> >> --- a/libavcodec/mpc7.c
> >> +++ b/libavcodec/mpc7.c
> >> @@ -61,6 +61,13 @@ static av_cold int mpc7_decode_init(AVCodecContext *
> >> avctx)
> >> static VLC_TYPE hdr_table[1 << MPC7_HDR_BITS][2];
> >> static VLC_TYPE quant_tables[7224][2];
> >>
> >> + /* Musepack SV7 is always stereo */
> >> + if (avctx->channels != 2) {
> >> + av_log_ask_for_sample(avctx, "Unsupported number of channels:
> >> %d\n",
> >> + avctx->channels);
> >> + return AVERROR_PATCHWELCOME;
> >> + }
> >> +
> >> if(avctx->extradata_size < 16){
> >> av_log(avctx, AV_LOG_ERROR, "Too small extradata size (%i)!\n",
> >> avctx->extradata_size);
> >> return -1;
> >> @@ -88,7 +95,7 @@ static av_cold int mpc7_decode_init(AVCodecContext *
> >> avctx)
> >> c->frames_to_skip = 0;
> >>
> >> avctx->sample_fmt = AV_SAMPLE_FMT_S16;
> >> - avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO :
> >> AV_CH_LAYOUT_MONO;
> >> + avctx->channel_layout = AV_CH_LAYOUT_STEREO;
> >>
> >> if(vlc_initialized) return 0;
> >> av_log(avctx, AV_LOG_DEBUG, "Initing VLC\n");
> >> --
> >
> > Yes, but it still lies to be mono. There was an issue with one such file.
>
>
> What do you mean it lies?
>
> The decoder assumes 2 channels everywhere.
Decoder - yes, but container may (and sometimes does) claim it has only one
channel and in this case the second channel should be ignored.
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