Vorbisfile API addition for game and mod coders;

Do a 'free' sample rate conversion from source rate to half source
rate by calling ov_halfrate() after ov_open(); Although this is solid
for immediately desired usage, I want to clean it up a bit before
advertising it's existence, so no doc addition yet.

Does not break binary API.

Monty

svn path=/trunk/vorbis/; revision=5222

1 files changed, 16 insertions, 1 deletions

diff --git a/lib/synthesis.c b/lib/synthesis.c
index ec3f5bfc..d645c5ab 100644
--- a/lib/synthesis.c
+++ b/lib/synthesis.c
@@ -11,7 +11,7 @@
  ********************************************************************
 
  function: single-block PCM synthesis
- last mod: $Id: synthesis.c,v 1.29 2002/10/11 11:14:41 xiphmont Exp $
+ last mod: $Id: synthesis.c,v 1.30 2003/08/18 05:34:01 xiphmont Exp $
 
  ********************************************************************/
 
@@ -152,4 +152,19 @@ long vorbis_packet_blocksize(vorbis_info *vi,ogg_packet *op){
   return(ci->blocksizes[ci->mode_param[mode]->blockflag]);
 }
 
+int vorbis_synthesis_halfrate(vorbis_info *vi,int flag){
+  /* set / clear half-sample-rate mode */
+  codec_setup_info     *ci=vi->codec_setup;
+  
+  /* right now, our MDCT can't handle < 64 sample windows. */
+  if(ci->blocksizes[0]<=64 && flag)return -1;
+  ci->halfrate_flag=(flag?1:0);
+  return 0;
+}
+
+int vorbis_synthesis_halfrate_p(vorbis_info *vi){
+  codec_setup_info     *ci=vi->codec_setup;
+  return ci->halfrate_flag;
+}
+