Revision 282255bb
| libavcodec/ac3enc.c | ||
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| 1295 | 1295 |
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| 1296 | 1296 |
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| 1297 | 1297 |
/** |
| 1298 |
* Set bandwidth for all channels. |
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* The user can optionally supply a cutoff frequency. Otherwise an appropriate |
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* default value will be used. |
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*/ |
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static av_cold void set_bandwidth(AC3EncodeContext *s, int cutoff) |
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{
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int ch, bw_code; |
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if (cutoff) {
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/* calculate bandwidth based on user-specified cutoff frequency */ |
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int fbw_coeffs; |
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cutoff = av_clip(cutoff, 1, s->sample_rate >> 1); |
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fbw_coeffs = cutoff * 2 * AC3_MAX_COEFS / s->sample_rate; |
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bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60); |
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} else {
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/* use default bandwidth setting */ |
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/* XXX: should compute the bandwidth according to the frame |
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size, so that we avoid annoying high frequency artifacts */ |
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bw_code = 50; |
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} |
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/* set number of coefficients for each channel */ |
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for (ch = 0; ch < s->fbw_channels; ch++) {
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s->bandwidth_code[ch] = bw_code; |
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s->nb_coefs[ch] = bw_code * 3 + 73; |
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} |
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if (s->lfe_on) |
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s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */ |
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} |
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/** |
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* Initialize the encoder. |
| 1299 | 1331 |
*/ |
| 1300 | 1332 |
static av_cold int ac3_encode_init(AVCodecContext *avctx) |
| 1301 | 1333 |
{
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| 1302 | 1334 |
AC3EncodeContext *s = avctx->priv_data; |
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int ch, bw_code, ret;
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int ret; |
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| 1304 | 1336 |
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avctx->frame_size = AC3_FRAME_SIZE; |
| 1306 | 1338 |
|
| ... | ... | |
| 1318 | 1350 |
s->samples_written = 0; |
| 1319 | 1351 |
s->frame_size = s->frame_size_min; |
| 1320 | 1352 |
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/* set bandwidth */ |
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if (avctx->cutoff) {
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/* calculate bandwidth based on user-specified cutoff frequency */ |
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int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1); |
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int fbw_coeffs = cutoff * 2 * AC3_MAX_COEFS / s->sample_rate; |
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bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60); |
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} else {
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/* use default bandwidth setting */ |
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/* XXX: should compute the bandwidth according to the frame |
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size, so that we avoid annoying high frequency artifacts */ |
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bw_code = 50; |
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} |
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for (ch = 0; ch < s->fbw_channels; ch++) {
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/* bandwidth for each channel */ |
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s->bandwidth_code[ch] = bw_code; |
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s->nb_coefs[ch] = bw_code * 3 + 73; |
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} |
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if (s->lfe_on) |
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s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */ |
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set_bandwidth(s, avctx->cutoff); |
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| 1340 | 1354 |
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| 1341 | 1355 |
/* initial snr offset */ |
| 1342 | 1356 |
s->coarse_snr_offset = 40; |
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