Fix decoding of multichannel flac, refactor sample buffer handling and decorrelation (taken from ffmpeg sources) and add some flac details to the manual. Solves FS#12371.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31207 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andree Buschmann
parent
09722dd28d
commit
a6653a9bb6
4 changed files with 42 additions and 70 deletions
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@ -27,6 +27,7 @@ CODEC_HEADER
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/* The output buffers containing the decoded samples (channels 0 and 1) */
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static int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_DECODED0;
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static int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR;
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static int32_t dummydec[MAX_BLOCKSIZE];
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#define MAX_SUPPORTED_SEEKTABLE_SIZE 5000
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@ -80,11 +81,26 @@ static bool flac_init(FLACContext* fc, int first_frame_offset)
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uint16_t blocksize;
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int endofmetadata=0;
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uint32_t blocklength;
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int ch;
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ci->memset(fc,0,sizeof(FLACContext));
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nseekpoints=0;
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fc->sample_skip = 0;
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/* Reset sample buffers */
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memset(decoded0, 0, sizeof(decoded0));
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memset(decoded1, 0, sizeof(decoded1));
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memset(dummydec, 0, sizeof(dummydec));
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/* Set sample buffers in decoder structure */
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fc->decoded[0] = decoded0;
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fc->decoded[1] = decoded1;
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for (ch=2; ch<MAX_CHANNELS; ++ch)
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{
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/* Only channel 0 and 1 are used, the other are decoded to scratch */
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fc->decoded[ch] = dummydec;
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}
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/* Skip any foreign tags at start of file */
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ci->seek_buffer(first_frame_offset);
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@ -231,7 +247,7 @@ static bool frame_sync(FLACContext* fc) {
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/* Decode the frame to verify the frame crc and
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* fill fc with its metadata.
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*/
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if(flac_decode_frame(fc, decoded0, decoded1,
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if(flac_decode_frame(fc,
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bit_buffer, buff_size, ci->yield) < 0) {
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return false;
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}
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@ -485,7 +501,7 @@ enum codec_status codec_run(void)
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ci->seek_complete();
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}
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if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
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if((res=flac_decode_frame(&fc,buf,
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bytesleft,ci->yield)) < 0) {
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LOGF("FLAC: Frame %d, error %d\n",frame,res);
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return CODEC_ERROR;
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@ -494,7 +510,7 @@ enum codec_status codec_run(void)
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frame++;
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ci->yield();
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ci->pcmbuf_insert(&decoded0[fc.sample_skip], &decoded1[fc.sample_skip],
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ci->pcmbuf_insert(&fc.decoded[0][fc.sample_skip], &fc.decoded[1][fc.sample_skip],
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fc.blocksize - fc.sample_skip);
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fc.sample_skip = 0;
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@ -381,17 +381,13 @@ static inline int decode_subframe(FLACContext *s, int channel, int32_t* decoded)
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}
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static int decode_frame(FLACContext *s,
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int32_t* decoded0,
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int32_t* decoded1,
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void (*yield)(void)) ICODE_ATTR_FLAC;
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static int decode_frame(FLACContext *s,
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int32_t* decoded0,
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int32_t* decoded1,
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void (*yield)(void))
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{
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int blocksize_code, sample_rate_code, sample_size_code, assignment, crc8;
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int decorrelation, bps, blocksize, samplerate;
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int res;
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int res, ch;
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blocksize_code = get_bits(&s->gb, 4);
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@ -477,16 +473,10 @@ static int decode_frame(FLACContext *s,
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s->bps = bps;
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s->decorrelation= decorrelation;
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yield();
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/* subframes */
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if ((res=decode_subframe(s, 0, decoded0)) < 0)
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return res-100;
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yield();
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if (s->channels==2) {
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if ((res=decode_subframe(s, 1, decoded1)) < 0)
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return res-200;
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for (ch=0; ch<s->channels; ++ch) {
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yield();
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if ((res=decode_subframe(s, ch, s->decoded[ch])) < 0)
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return res-100;
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}
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yield();
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@ -499,8 +489,6 @@ static int decode_frame(FLACContext *s,
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}
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int flac_decode_frame(FLACContext *s,
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int32_t* decoded0,
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int32_t* decoded1,
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uint8_t *buf, int buf_size,
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void (*yield)(void))
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{
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@ -516,68 +504,36 @@ int flac_decode_frame(FLACContext *s,
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return -41;
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}
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if ((framesize=decode_frame(s,decoded0,decoded1,yield)) < 0){
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if ((framesize=decode_frame(s,yield)) < 0){
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s->bitstream_size=0;
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s->bitstream_index=0;
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return framesize;
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}
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yield();
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#define DECORRELATE(left, right)\
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for (i = 0; i < s->blocksize; i++) {\
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int a = s->decoded[0][i];\
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int b = s->decoded[1][i];\
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s->decoded[0][i] = (left) << scale;\
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s->decoded[1][i] = (right) << scale;\
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}\
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scale=FLAC_OUTPUT_DEPTH-s->bps;
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switch(s->decorrelation)
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{
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case INDEPENDENT:
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if (s->channels==1) {;
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for (i = 0; i < s->blocksize; i++)
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{
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decoded0[i] = decoded0[i] << scale;
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}
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} else {
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for (i = 0; i < s->blocksize; i++)
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{
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decoded0[i] = decoded0[i] << scale;
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decoded1[i] = decoded1[i] << scale;
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}
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}
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DECORRELATE(a, b) /* Always decorrelate exactly the two supported channels. */
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break;
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case LEFT_SIDE:
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//assert(s->channels == 2);
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for (i = 0; i < s->blocksize; i++)
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{
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decoded1[i] = (decoded0[i] - decoded1[i]) << scale;
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decoded0[i] = decoded0[i] << scale;
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}
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DECORRELATE(a, a-b)
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break;
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case RIGHT_SIDE:
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//assert(s->channels == 2);
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for (i = 0; i < s->blocksize; i++)
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{
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decoded0[i] = (decoded0[i] + decoded1[i]) << scale;
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decoded1[i] = decoded1[i] << scale;
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}
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DECORRELATE(a+b, a)
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break;
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case MID_SIDE:
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//assert(s->channels == 2);
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for (i = 0; i < s->blocksize; i++)
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{
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int mid, side;
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mid = decoded0[i];
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side = decoded1[i];
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#if 1 //needs to be checked but IMHO it should be binary identical
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mid -= side>>1;
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decoded0[i] = (mid + side) << scale;
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decoded1[i] = mid << scale;
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#else
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mid <<= 1;
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if (side & 1)
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mid++;
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decoded0[i] = ((mid + side) >> 1) << scale;
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decoded1[i] = ((mid - side) >> 1) << scale;
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#endif
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}
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DECORRELATE( (a-=b>>1) + b, a)
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break;
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}
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@ -3,9 +3,9 @@
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#include "bitstream.h"
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#define MAX_CHANNELS 2 /* Maximum supported channels */
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#define MAX_CHANNELS 6 /* Maximum supported channels, only left/right will be played back */
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#define MAX_BLOCKSIZE 4608 /* Maxsize in samples of one uncompressed frame */
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#define MAX_FRAMESIZE 32768 /* Maxsize in bytes of one compressed frame */
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#define MAX_FRAMESIZE 65536 /* Maxsize in bytes of one compressed frame */
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#define FLAC_OUTPUT_DEPTH 29 /* Provide samples left-shifted to 28 bits+sign */
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@ -38,11 +38,11 @@ typedef struct FLACContext {
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int sample_skip;
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int framesize;
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int32_t *decoded[MAX_CHANNELS];
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} FLACContext;
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int flac_decode_frame(FLACContext *s,
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int32_t* decoded0,
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int32_t* decoded1,
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uint8_t *buf, int buf_size,
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void (*yield)(void)) ICODE_ATTR_FLAC;
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@ -176,7 +176,7 @@
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& Linear PCM 8/16/24/32 bit, IEEE float 32/64 bit, ITU-T G.711 a-law/$\mu$-law\\
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Free Lossless Audio
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& \fname{.flac}
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& \\
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& Supports multichannel tracks w/o downmixing (only left/right is played).\\
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Apple Lossless
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& \fname{.m4a}, \fname{.mp4}
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& \\
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