user setable quantizer bias

Originally committed as revision 1701 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -15,8 +15,8 @@ extern "C" {
 
 #define LIBAVCODEC_VERSION_INT 0x000406
 #define LIBAVCODEC_VERSION     "0.4.6"
-#define LIBAVCODEC_BUILD       4662
-#define LIBAVCODEC_BUILD_STR   "4662"
+#define LIBAVCODEC_BUILD       4663
+#define LIBAVCODEC_BUILD_STR   "4663"
 
 #define LIBAVCODEC_IDENT	"FFmpeg" LIBAVCODEC_VERSION "b" LIBAVCODEC_BUILD_STR
 
@@ -1038,8 +1038,23 @@ typedef struct AVCodecContext {
      * - decoding: set by lavc.
      * @todo move this after frame_rate
      */
-    int frame_rate_base;
 
+    int frame_rate_base;
+    /**
+     * intra quantizer bias.
+     * - encoding: set by user.
+     * - decoding: unused
+     */
+    int intra_quant_bias;
+#define FF_DEFAULT_QUANT_BIAS 999999
+    
+    /**
+     * inter quantizer bias.
+     * - encoding: set by user.
+     * - decoding: unused
+     */
+    int inter_quant_bias;
+    
 } AVCodecContext;
 
 

libavcodec/h263.c

@@ -1484,14 +1484,6 @@ void h263_encode_init(MpegEncContext *s)
         s->y_dc_scale_table=
         s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
     }
-
-    if(s->mpeg_quant){
-        s->intra_quant_bias= 3<<(QUANT_BIAS_SHIFT-3); //(a + x*3/8)/x
-        s->inter_quant_bias= 0;
-    }else{
-        s->intra_quant_bias=0;
-        s->inter_quant_bias=-(1<<(QUANT_BIAS_SHIFT-2)); //(a - x/4)/x
-    }
 }
 
 /**

libavcodec/mjpeg.c

@@ -251,7 +251,6 @@ int mjpeg_init(MpegEncContext *s)
     
     s->min_qcoeff=-1023;
     s->max_qcoeff= 1023;
-    s->intra_quant_bias= 1<<(QUANT_BIAS_SHIFT-1); //(a + x/2)/x
 
     /* build all the huffman tables */
     build_huffman_codes(m->huff_size_dc_luminance,

libavcodec/mpeg12.c

@@ -702,8 +702,6 @@ void ff_mpeg1_encode_init(MpegEncContext *s)
     s->fcode_tab= fcode_tab;
     s->min_qcoeff=-255;
     s->max_qcoeff= 255;
-    s->intra_quant_bias= 3<<(QUANT_BIAS_SHIFT-3); //(a + x*3/8)/x
-    s->inter_quant_bias= 0;
     s->intra_ac_vlc_length=
     s->inter_ac_vlc_length= uni_mpeg1_ac_vlc_len;
 }

libavcodec/mpegvideo.c

@@ -551,6 +551,22 @@ int MPV_encode_init(AVCodecContext *avctx)
     
     s->progressive_sequence= !(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
 
+    if(s->codec_id==CODEC_ID_MJPEG){
+        s->intra_quant_bias= 1<<(QUANT_BIAS_SHIFT-1); //(a + x/2)/x
+        s->inter_quant_bias= 0;
+    }else if(s->mpeg_quant || s->codec_id==CODEC_ID_MPEG1VIDEO){
+        s->intra_quant_bias= 3<<(QUANT_BIAS_SHIFT-3); //(a + x*3/8)/x
+        s->inter_quant_bias= 0;
+    }else{
+        s->intra_quant_bias=0;
+        s->inter_quant_bias=-(1<<(QUANT_BIAS_SHIFT-2)); //(a - x/4)/x
+    }
+    
+    if(avctx->intra_quant_bias != FF_DEFAULT_QUANT_BIAS)
+        s->intra_quant_bias= avctx->intra_quant_bias;
+    if(avctx->inter_quant_bias != FF_DEFAULT_QUANT_BIAS)
+        s->inter_quant_bias= avctx->inter_quant_bias;
+    
     switch(avctx->codec->id) {
     case CODEC_ID_MPEG1VIDEO:
         s->out_format = FMT_MPEG1;

libavcodec/mpegvideo.h

@@ -360,7 +360,7 @@ typedef struct MpegEncContext {
     uint16_t chroma_intra_matrix[64];
     uint16_t inter_matrix[64];
     uint16_t chroma_inter_matrix[64];
-#define QUANT_BIAS_SHIFT 4
+#define QUANT_BIAS_SHIFT 8
     int intra_quant_bias;    ///< bias for the quantizer 
     int inter_quant_bias;    ///< bias for the quantizer 
     int min_qcoeff;          ///< minimum encodable coefficient 

libavcodec/utils.c

@@ -244,6 +244,9 @@ void avcodec_get_context_defaults(AVCodecContext *s){
     s->release_buffer= avcodec_default_release_buffer;
     s->get_format= avcodec_default_get_format;
     s->me_subpel_quality=8;
+    
+    s->intra_quant_bias= FF_DEFAULT_QUANT_BIAS;
+    s->inter_quant_bias= FF_DEFAULT_QUANT_BIAS;
 }
 
 /**