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alacdec: implement the 2-pass prediction type. 

The reference encoder does not generate any streams using this, but the
reference decoder can handle it, so we should as well.
This commit is contained in:
Justin Ruggles 2011-12-07 11:56:57 -05:00
parent bb63475aec
commit e49d21306a
1 changed files with 21 additions and 16 deletions
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37
libavcodec/alac.c
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@ -452,24 +452,29 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
ricemodifier[ch] * alac->setinfo_rice_historymult / 4,
(1 << alac->setinfo_rice_kmodifier) - 1);
if (prediction_type[ch] == 0) {
/* adaptive fir */
predictor_decompress_fir_adapt(alac->predicterror_buffer[ch],
alac->outputsamples_buffer[ch],
outputsamples,
readsamplesize,
predictor_coef_table[ch],
predictor_coef_num[ch],
prediction_quantitization[ch]);
} else {
av_log(avctx, AV_LOG_ERROR, "FIXME: unhandled prediction type: %i\n", prediction_type[ch]);
/* I think the only other prediction type (or perhaps this is
* just a boolean?) runs adaptive fir twice.. like:
* predictor_decompress_fir_adapt(predictor_error, tempout, ...)
* predictor_decompress_fir_adapt(predictor_error, outputsamples ...)
* little strange..
/* adaptive FIR filter */
if (prediction_type[ch] == 15) {
/* Prediction type 15 runs the adaptive FIR twice.
* The first pass uses the special-case coef_num = 31, while
* the second pass uses the coefs from the bitstream.
*
* However, this prediction type is not currently used by the
* reference encoder.
*/
predictor_decompress_fir_adapt(alac->predicterror_buffer[ch],
alac->predicterror_buffer[ch],
outputsamples, readsamplesize,
NULL, 31, 0);
} else if (prediction_type[ch] > 0) {
av_log(avctx, AV_LOG_WARNING, "unknown prediction type: %i\n",
prediction_type[ch]);
}
predictor_decompress_fir_adapt(alac->predicterror_buffer[ch],
alac->outputsamples_buffer[ch],
outputsamples, readsamplesize,
predictor_coef_table[ch],
predictor_coef_num[ch],
prediction_quantitization[ch]);
}
} else {
/* not compressed, easy case */