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

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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
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@ -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
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@ -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},
};