[FFmpeg-devel] [PATCH] floating-point input to libvorbis encoder

[Michael Niedermayer]

On Mon, Sep 20, 2010 at 08:32:46AM +0100, M?ns Rullg?rd wrote:
> Tomas H?rdin <tomas.hardin at codemill.se> writes:
> 
> > On Sat, 2010-09-18 at 12:12 -0400, Justin Ruggles wrote:
> >> Hi,
> >> 
> >> libvorbis takes floating-point samples as input.  Our libvorbis wrapper
> >> currently only accepts 16-bit input and converts it to float.  It seems
> >> better to me to have it only accept float input and leave the conversion
> >> outside of the encoder.
> >> 
> >> -Justin
> >> 
> >> plain text document attachment (libvorbis_float_input.patch)
> >> Index: libavcodec/libvorbis.c
> >> ===================================================================
> >> --- libavcodec/libvorbis.c	(revision 25138)
> >> +++ libavcodec/libvorbis.c	(working copy)
> >> @@ -145,7 +145,7 @@
> >>  {
> >>      OggVorbisContext *context = avccontext->priv_data ;
> >>      ogg_packet op ;
> >> -    signed short *audio = data ;
> >> +    float *audio = data;
> >>      int l;
> >>  
> >>      if(data) {
> >> @@ -158,7 +158,7 @@
> >>              int co = (channels > 8) ? c :
> >>                  ff_vorbis_encoding_channel_layout_offsets[channels-1][c];
> >>              for(l = 0 ; l < samples ; l++)
> >> -                buffer[c][l]=audio[l*channels+co]/32768.f;
> >> +                buffer[c][l] = audio[l*channels+co];
> >>          }
> >>          vorbis_analysis_wrote(&context->vd, samples) ;
> >>      } else {
> >> @@ -238,6 +238,6 @@
> >>      oggvorbis_encode_frame,
> >>      oggvorbis_encode_close,
> >>      .capabilities= CODEC_CAP_DELAY,
> >> -    .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
> >> +    .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_FLT,SAMPLE_FMT_NONE},
> >>      .long_name= NULL_IF_CONFIG_SMALL("libvorbis Vorbis"),
> >>  } ;
> >
> > Please correct me if I'm wrong, but doesn't this require a major version
> > bump?
> 
> Strictly speaking, no.  The codec exports the list of supported input
> formats, and a proper app should perform any conversions necessary.
> That said, there are probably many apps assuming s16 is supported, and
> they would indeed be broken by this change.  Do we care about those?

in this case i dont think we care, apps should implement the api properly
and its quite trivial to fix an app that does not

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Into a blind darkness they enter who follow after the Ignorance,
they as if into a greater darkness enter who devote themselves
to the Knowledge alone. -- Isha Upanishad
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