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ac3enc: do not store a bandwidth code for each channel.

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Although AC-3 allows it, it's not very useful. The encoder uses the same code
for all full-bandwidth channels.
This commit is contained in:
Justin Ruggles 2011-04-15 22:49:05 -04:00
parent a1d0f511fc
commit 177fed4e9b
1 changed files with 6 additions and 7 deletions
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13
libavcodec/ac3enc.c
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@ -162,7 +162,7 @@ typedef struct AC3EncodeContext {
int loro_surround_mix_level; ///< Lo/Ro surround mix level code
int cutoff; ///< user-specified cutoff frequency, in Hz
int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod)
int bandwidth_code; ///< bandwidth code (0 to 60) (chbwcod)
int nb_coefs[AC3_MAX_CHANNELS];
int rematrixing_enabled; ///< stereo rematrixing enabled
@ -1407,7 +1407,7 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
/* bandwidth */
for (ch = 0; ch < s->fbw_channels; ch++) {
if (s->exp_strategy[ch][blk] != EXP_REUSE)
put_bits(&s->pb, 6, s->bandwidth_code[ch]);
put_bits(&s->pb, 6, s->bandwidth_code);
}
/* exponents */
@ -2047,22 +2047,21 @@ static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
*/
static av_cold void set_bandwidth(AC3EncodeContext *s)
{
int ch, bw_code;
int ch;
if (s->cutoff) {
/* calculate bandwidth based on user-specified cutoff frequency */
int fbw_coeffs;
fbw_coeffs = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
s->bandwidth_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
} else {
/* use default bandwidth setting */
bw_code = ac3_bandwidth_tab[s->fbw_channels-1][s->bit_alloc.sr_code][s->frame_size_code/2];
s->bandwidth_code = ac3_bandwidth_tab[s->fbw_channels-1][s->bit_alloc.sr_code][s->frame_size_code/2];
}
/* set number of coefficients for each channel */
for (ch = 0; ch < s->fbw_channels; ch++) {
s->bandwidth_code[ch] = bw_code;
s->nb_coefs[ch] = bw_code * 3 + 73;
s->nb_coefs[ch] = s->bandwidth_code * 3 + 73;
}
if (s->lfe_on)
s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */