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Add option for user to scale the amount of dynamic range compression which is 

applied by the audio decoder, and use that option in the AC3 decoder.

Originally committed as revision 11280 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-12-20 00:55:08 +00:00
parent cd31f8dc23
commit 1408352ada
3 changed files with 11 additions and 1 deletions
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3
libavcodec/ac3dec.c
View File

@ -792,7 +792,8 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
i = !(ctx->channel_mode);
do {
if(get_bits1(gb)) {
ctx->dynamic_range[i] = dynamic_range_tab[get_bits(gb, 8)];
ctx->dynamic_range[i] = ((dynamic_range_tab[get_bits(gb, 8)]-1.0) *
ctx->avctx->drc_scale)+1.0;
} else if(blk == 0) {
ctx->dynamic_range[i] = 1.0f;
}

8
libavcodec/avcodec.h
View File

@ -2154,6 +2154,14 @@ typedef struct AVCodecContext {
* - decoding: Set by user.
*/
int request_channels;
/**
* Percentage of dynamic range compression to be applied by the decoder.
* The default value is 1.0, corresponding to full compression.
* - encoding: unused
* - decoding: Set by user.
*/
float drc_scale;
} AVCodecContext;
/**

1
libavcodec/utils.c
View File

@ -761,6 +761,7 @@ static const AVOption options[]={
{"drop_frame_timecode", NULL, 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_DROP_FRAME_TIMECODE, INT_MIN, INT_MAX, V|E, "flags2"},
{"non_linear_q", "use non linear quantizer", 0, FF_OPT_TYPE_CONST, CODEC_FLAG2_NON_LINEAR_QUANT, INT_MIN, INT_MAX, V|E, "flags2"},
{"request_channels", "set desired number of audio channels", OFFSET(request_channels), FF_OPT_TYPE_INT, DEFAULT, 0, INT_MAX, A|D},
{"drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), FF_OPT_TYPE_FLOAT, 1.0, 0.0, 1.0, A|D},
{NULL},
};