* @author 2005 David Hammerton
* @see http://crazney.net/programs/itunes/alac.html
*
- * Note: This decoder expects a 36- (0x24-)byte QuickTime atom to be
+ * Note: This decoder expects a 36-byte QuickTime atom to be
* passed through the extradata[_size] fields. This atom is tacked onto
* the end of an 'alac' stsd atom and has the following format:
- * bytes 0-3 atom size (0x24), big-endian
- * bytes 4-7 atom type ('alac', not the 'alac' tag from start of stsd)
- * bytes 8-35 data bytes needed by decoder
*
- * Extradata:
- * 32bit size
- * 32bit tag (=alac)
- * 32bit zero?
- * 32bit max sample per frame
- * 8bit ?? (zero?)
+ * 32bit atom size
+ * 32bit tag ("alac")
+ * 32bit tag version (0)
+ * 32bit samples per frame (used when not set explicitly in the frames)
+ * 8bit compatible version (0)
* 8bit sample size
- * 8bit history mult
- * 8bit initial history
- * 8bit kmodifier
- * 8bit channels?
- * 16bit ??
- * 32bit max coded frame size
- * 32bit bitrate?
+ * 8bit history mult (40)
+ * 8bit initial history (14)
+ * 8bit kmodifier (10)
+ * 8bit channels
+ * 16bit maxRun (255)
+ * 32bit max coded frame size (0 means unknown)
+ * 32bit average bitrate (0 means unknown)
* 32bit samplerate
*/
return x;
}
-static void bastardized_rice_decompress(ALACContext *alac,
+static int bastardized_rice_decompress(ALACContext *alac,
int32_t *output_buffer,
int output_size,
int readsamplesize, /* arg_10 */
/* standard rice encoding */
int k; /* size of extra bits */
+ if(get_bits_left(&alac->gb) <= 0)
+ return -1;
+
/* read k, that is bits as is */
k = av_log2((history >> 9) + 3);
x= decode_scalar(&alac->gb, k, rice_kmodifier, readsamplesize);
history = 0;
}
}
+ return 0;
}
static inline int sign_only(int v)
if (alac->extra_bits) {
for (i = 0; i < outputsamples; i++) {
+ if(get_bits_left(&alac->gb) <= 0)
+ return -1;
for (ch = 0; ch < channels; ch++)
alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits);
}
}
for (ch = 0; ch < channels; ch++) {
- bastardized_rice_decompress(alac,
+ int ret = bastardized_rice_decompress(alac,
alac->predicterror_buffer[ch],
outputsamples,
readsamplesize,
alac->setinfo_rice_kmodifier,
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..
+ if(ret<0)
+ return ret;
+
+ /* 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 */
for (i = 0; i < outputsamples; i++) {
+ if(get_bits_left(&alac->gb) <= 0)
+ return -1;
for (ch = 0; ch < channels; ch++) {
alac->outputsamples_buffer[ch][i] = get_sbits_long(&alac->gb,
alac->setinfo_sample_size);
ptr += 4; /* size */
ptr += 4; /* alac */
- ptr += 4; /* 0 ? */
+ ptr += 4; /* version */
if(AV_RB32(ptr) >= UINT_MAX/4){
av_log(alac->avctx, AV_LOG_ERROR, "setinfo_max_samples_per_frame too large\n");
/* buffer size / 2 ? */
alac->setinfo_max_samples_per_frame = bytestream_get_be32(&ptr);
- ptr++; /* ??? */
+ ptr++; /* compatible version */
alac->setinfo_sample_size = *ptr++;
alac->setinfo_rice_historymult = *ptr++;
alac->setinfo_rice_initialhistory = *ptr++;
alac->setinfo_rice_kmodifier = *ptr++;
alac->numchannels = *ptr++;
- bytestream_get_be16(&ptr); /* ??? */
+ bytestream_get_be16(&ptr); /* maxRun */
bytestream_get_be32(&ptr); /* max coded frame size */
- bytestream_get_be32(&ptr); /* bitrate ? */
+ bytestream_get_be32(&ptr); /* average bitrate */
bytestream_get_be32(&ptr); /* samplerate */
return 0;
projects / ffmpeg / blobdiff