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rockbox/apps/codecs/flac.c
Dave Chapman 15a830bdba Skip ID3v2 tags at the start of a FLAC file. 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7689 a1c6a512-1295-4272-9138-f99709370657
2005-10-30 15:07:40 +00:00

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9.1 KiB
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2005 Dave Chapman
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "codeclib.h"
#include <codecs/libffmpegFLAC/decoder.h>
#ifndef SIMULATOR
extern char iramcopy[];
extern char iramstart[];
extern char iramend[];
#endif
struct codec_api* rb;
struct codec_api* ci;
/* The output buffers containing the decoded samples (channels 0 and 1) */
int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR;
int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR;
#define MAX_SUPPORTED_SEEKTABLE_SIZE 5000
/* Notes about seeking:
The full seek table consists of:
uint64_t sample (only 36 bits are used)
uint64_t offset
uint32_t blocksize
We don't store the blocksize (of the target frame) and we also
limit the sample and offset values to 32-bits - Rockbox doesn't support
files bigger than 2GB on FAT32 filesystems.
The reference FLAC encoder produces a seek table with points every
10 seconds, but this can be overridden by the user when encoding a file.
With the default settings, a typical 4 minute track will contain
24 seek points.
Taking the extreme case of a Rockbox supported file to be a 2GB (compressed)
16-bit/44.1KHz mono stream with a likely uncompressed size of 4GB:
Total duration is: 48694 seconds (about 810 minutes - 13.5 hours)
Total number of seek points: 4869
Therefore we limit the number of seek points to 5000. This is a
very extreme case, and requires 5000*8=40000 bytes of storage.
If we come across a FLAC file with more than this number of seekpoints, we
just use the first 5000.
*/
struct FLACseekpoints {
uint32_t sample;
uint32_t offset;
};
struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
int nseekpoints;
static bool flac_init(FLACContext* fc, int first_frame_offset)
{
unsigned char buf[255];
bool found_streaminfo=false;
uint32_t seekpoint_hi,seekpoint_lo;
uint32_t offset_hi,offset_lo;
int endofmetadata=0;
int blocklength;
int n;
uint32_t* p;
ci->memset(fc,0,sizeof(FLACContext));
nseekpoints=0;
/* Skip any foreign tags at start of file */
ci->seek_buffer(first_frame_offset);
fc->metadatalength = first_frame_offset;
if (ci->read_filebuf(buf, 4) < 4)
{
return false;
}
if (ci->memcmp(buf,"fLaC",4) != 0)
{
return false;
}
fc->metadatalength += 4;
while (!endofmetadata) {
if (ci->read_filebuf(buf, 4) < 4)
{
return false;
}
endofmetadata=(buf[0]&0x80);
blocklength = (buf[1] << 16) | (buf[2] << 8) | buf[3];
fc->metadatalength+=blocklength+4;
if ((buf[0] & 0x7f) == 0) /* 0 is the STREAMINFO block */
{
/* FIXME: Don't trust the value of blocklength */
if (ci->read_filebuf(buf, blocklength) < 0)
{
return false;
}
fc->filesize = ci->filesize;
fc->min_blocksize = (buf[0] << 8) | buf[1];
fc->max_blocksize = (buf[2] << 8) | buf[3];
fc->min_framesize = (buf[4] << 16) | (buf[5] << 8) | buf[6];
fc->max_framesize = (buf[7] << 16) | (buf[8] << 8) | buf[9];
fc->samplerate = (buf[10] << 12) | (buf[11] << 4)
| ((buf[12] & 0xf0) >> 4);
fc->channels = ((buf[12]&0x0e)>>1) + 1;
fc->bps = (((buf[12]&0x01) << 4) | ((buf[13]&0xf0)>>4) ) + 1;
/* totalsamples is a 36-bit field, but we assume <= 32 bits are
used */
fc->totalsamples = (buf[14] << 24) | (buf[15] << 16)
| (buf[16] << 8) | buf[17];
/* Calculate track length (in ms) and estimate the bitrate
(in kbit/s) */
fc->length = (fc->totalsamples / fc->samplerate) * 1000;
found_streaminfo=true;
} else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
(blocklength >= 18)) {
n=ci->read_filebuf(buf,18);
if (n < 18) return false;
blocklength-=n;
p=(uint32_t*)buf;
seekpoint_hi=betoh32(*(p++));
seekpoint_lo=betoh32(*(p++));
offset_hi=betoh32(*(p++));
offset_lo=betoh32(*(p++));
if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
(offset_hi == 0)) {
seekpoints[nseekpoints].sample=seekpoint_lo;
seekpoints[nseekpoints].offset=offset_lo;
nseekpoints++;
}
}
/* Skip any unread seekpoints */
if (blocklength > 0)
ci->advance_buffer(blocklength);
} else {
/* Skip to next metadata block */
ci->advance_buffer(blocklength);
}
}
if (found_streaminfo) {
fc->bitrate = ((fc->filesize-fc->metadatalength) * 8) / fc->length;
return true;
} else {
return false;
}
}
/* A very simple seek implementation - seek to the seekpoint before
the target sample.
This needs to be improved to seek with greater accuracy
*/
bool flac_seek(FLACContext* fc, uint32_t newsample) {
uint32_t offset;
int i;
if (nseekpoints==0) {
offset=0;
} else {
i=nseekpoints-1;
while ((i > 0) && (seekpoints[i].sample > newsample)) {
i--;
}
if ((i==0) && (seekpoints[i].sample > newsample)) {
offset=0;
} else {
offset=seekpoints[i].offset;
}
}
offset+=fc->metadatalength;
if (ci->seek_buffer(offset)) {
return true;
} else {
return false;
}
}
/* this is the codec entry point */
enum codec_status codec_start(struct codec_api* api)
{
int8_t *buf;
FLACContext fc;
uint32_t samplesdone;
uint32_t elapsedtime;
long bytesleft;
int consumed;
int res;
int frame;
/* Generic codec initialisation */
TEST_CODEC_API(api);
rb = api;
ci = (struct codec_api*)api;
#ifndef SIMULATOR
ci->memcpy(iramstart, iramcopy, iramend-iramstart);
#endif
ci->configure(CODEC_SET_FILEBUF_LIMIT, (int *)(1024*1024*10));
ci->configure(CODEC_SET_FILEBUF_WATERMARK, (int *)(1024*512));
ci->configure(CODEC_SET_FILEBUF_CHUNKSIZE, (int *)(1024*128));
ci->configure(CODEC_DSP_ENABLE, (bool *)true);
ci->configure(DSP_DITHER, (bool *)false);
ci->configure(DSP_SET_STEREO_MODE, (long *)STEREO_NONINTERLEAVED);
ci->configure(DSP_SET_SAMPLE_DEPTH, (int *)(28));
next_track:
if (codec_init(api)) {
LOGF("FLAC: Error initialising codec\n");
return CODEC_ERROR;
}
if (!flac_init(&fc,ci->id3->first_frame_offset)) {
LOGF("FLAC: Error initialising codec\n");
return CODEC_ERROR;
}
while (!*ci->taginfo_ready)
ci->yield();
ci->configure(DSP_SET_FREQUENCY, (long *)(ci->id3->frequency));
/* The main decoding loop */
samplesdone=0;
frame=0;
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
while (bytesleft) {
ci->yield();
if (ci->stop_codec || ci->reload_codec) {
break;
}
/* Deal with any pending seek requests */
if (ci->seek_time) {
if (flac_seek(&fc,(ci->seek_time/20) * (ci->id3->frequency/50))) {
/* Refill the input buffer */
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
}
ci->seek_time = 0;
}
if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
bytesleft,ci->yield)) < 0) {
LOGF("FLAC: Frame %d, error %d\n",frame,res);
return CODEC_ERROR;
}
consumed=fc.gb.index/8;
frame++;
ci->yield();
while(!ci->pcmbuf_insert_split((char*)decoded0,(char*)decoded1,
fc.blocksize*4)) {
ci->yield();
}
/* Update the elapsed-time indicator */
samplesdone=fc.samplenumber+fc.blocksize;
elapsedtime=(samplesdone*10)/(ci->id3->frequency/100);
ci->set_elapsed(elapsedtime);
ci->advance_buffer(consumed);
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
}
LOGF("FLAC: Decoded %d samples\n",samplesdone);
if (ci->request_next_track())
goto next_track;
return CODEC_OK;
}
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