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simplify decoding of uncompressed samples. patch by matthieu castet <castet matthieu free fr>.

Originally committed as revision 13120 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Matthieu Castet 2008-05-11 18:13:30 +00:00 committed by Justin Ruggles
parent 907eb3b526
commit e5838c90ee

View File

@ -115,6 +115,10 @@ static int alac_set_info(ALACContext *alac)
alac->setinfo_max_samples_per_frame = bytestream_get_be32(&ptr);
ptr++; /* ??? */
alac->setinfo_sample_size = *ptr++;
if (alac->setinfo_sample_size > 32) {
av_log(alac->avctx, AV_LOG_ERROR, "setinfo_sample_size too large\n");
return -1;
}
alac->setinfo_rice_historymult = *ptr++;
alac->setinfo_rice_initialhistory = *ptr++;
alac->setinfo_rice_kmodifier = *ptr++;
@ -531,33 +535,16 @@ static int alac_decode_frame(AVCodecContext *avctx,
}
} else {
/* not compressed, easy case */
if (alac->setinfo_sample_size <= 16) {
int i, chan;
for (chan = 0; chan < channels; chan++)
for (i = 0; i < outputsamples; i++) {
int32_t audiobits;
audiobits = get_bits(&alac->gb, alac->setinfo_sample_size);
audiobits = extend_sign32(audiobits, readsamplesize);
audiobits = get_bits_long(&alac->gb, alac->setinfo_sample_size);
audiobits = extend_sign32(audiobits, alac->setinfo_sample_size);
alac->outputsamples_buffer[chan][i] = audiobits;
}
} else {
int i, chan;
for (chan = 0; chan < channels; chan++)
for (i = 0; i < outputsamples; i++) {
int32_t audiobits;
audiobits = get_bits(&alac->gb, 16);
/* special case of sign extension..
* as we'll be ORing the low 16bits into this */
audiobits = audiobits << 16;
audiobits = audiobits >> (32 - alac->setinfo_sample_size);
audiobits |= get_bits(&alac->gb, alac->setinfo_sample_size - 16);
alac->outputsamples_buffer[chan][i] = audiobits;
}
}
/* wasted_bytes = 0; */
interlacing_shift = 0;
interlacing_leftweight = 0;