[FFmpeg-devel] [PATCH] fix clicks in ADPCM IMA AMV decoder

[Vladimir Voroshilov]

2007/10/4, Aurelien Jacobs <aurel at gnuage.org>:
> Vladimir Voroshilov wrote:
>
> > 2007/10/4, Aurelien Jacobs <aurel at gnuage.org>:
> > > Vladimir Voroshilov wrote:
> > >
> > > > 2007/10/3, Vitor Sessak <vitor1001 at gmail.com>:
> > > > > Hi
> > > > >
> > > > > Vladimir Voroshilov wrote:
> > > > > > Hi, All
> > > > > >
> > > > > > Attached simle patches fixes clicks in audio when playing AMV files.
> > > > >
> > > > > Cool. Is it still not loud enough?
> > > >
> > > > Hm. It is enough loud for me now.
> > > >
> > > >
> > > > > >
> > > > > > Index: libavcodec/adpcm.c
> > > > > > ===================================================================
> > > > > > --- libavcodec/adpcm.c        (revision 10652)
> > > > > > +++ libavcodec/adpcm.c        (working copy)
> > > > > > @@ -1184,7 +1184,7 @@
> > > > > >          break;
> > > > > >      case CODEC_ID_ADPCM_IMA_AMV:
> > > > > >      case CODEC_ID_ADPCM_IMA_SMJPEG:
> > > > > > -        c->status[0].predictor = *src;
> > > > > > +        c->status[0].predictor = (int16_t)AV_RL16(src);
> > > > > >          src += 2;
> > > > >
> > > > > c->status[0].predictor = bytestream_get_le16(&src);
> > > >
> > > > I've made simple (imho) solution which also comply with other code style.
> > >
> > > This new patch is not good. It could segfault on arch which requires strict
> > > alignment if src is not properly aligned.
> > > The solution proposed by Vitor is the right one, and it's simpler (it saves
> > > you the src += 2).
> >
> > Thanks. Didn't know that.
> >
> > > BTW: I wonder if step_index shouldn't be read as an int16_t as well ?
> >
> > According to multimedia wiki it should.
> > This also also shows why fourth byte is always zero (index<=88)
> > Included in patch.
> >
> > Index: libavcodec/adpcm.c
> > ===================================================================
> > --- libavcodec/adpcm.c        (revision 10652)
> > +++ libavcodec/adpcm.c        (working copy)
> > @@ -1184,10 +1184,8 @@
> >          break;
> >      case CODEC_ID_ADPCM_IMA_AMV:
> >      case CODEC_ID_ADPCM_IMA_SMJPEG:
> > -        c->status[0].predictor = *src;
> > -        src += 2;
> > -        c->status[0].step_index = *src++;
> > -        src++;  /* skip another byte before getting to the meat */
> > +        c->status[0].predictor = (signed short)bytestream_get_le16(&src);
> > +        c->status[0].step_index = bytestream_get_le16(&src);
>
> I suppose the signed short cast is useless. If so, please remove it.
> If you remove it, you could also align the = sign.

Signed cast is required (exactly this signed cast removes clicks in sound).

> Except those remarks, patch is OK. I think you can apply it yourself.

Do i have write access :-O ?


-- 
Regards,
Vladimir Voroshilov     mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
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