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rockbox/lib/rbcodec/codecs/flac.c
Andrew Ryabinin b770f63934 flac: fix seeking. 
As comment in code states:
"It is possible for our seek to land in the middle of audio
data that looks exactly like a frame header from a future
version of an encoder.  When that happens, frame_sync() will
return false. But there is a remote possibility that it is
properly synced at such a "future-codec frame", so to make sure,
we wait to see several "unparseable" errors in a row before
bailing out."

Currently we wait for 10 "unparseable" errors. libFLAC waits for 20.
But I've got a valid flac+cue, wherein switching to certain track
gave me 24 "unparsaeable" errors. Therefore I increased
unparseable_count to 30.

Change-Id: I4e97a5385c729adf3d5075d41ea312622c69e548
Reviewed-on: http://gerrit.rockbox.org/658
Reviewed-by: Michael Giacomelli <giac2000@hotmail.com>
Reviewed-by: Boris Gjenero <boris.gjenero@gmail.com>
Tested-by: Andrew Ryabinin <ryabinin.a.a@gmail.com>
Reviewed-by: Andrew Ryabinin <ryabinin.a.a@gmail.com>
2013-11-18 07:45:59 +01:00

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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2005 Dave Chapman
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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>
CODEC_HEADER
static FLACContext fc IBSS_ATTR_FLAC;
/* The output buffers containing the decoded samples (channels 0 and 1) */
static int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR_FLAC;
static int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR_FLAC;
static int32_t decoded2[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_LARGE_IRAM;
static int32_t decoded3[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_LARGE_IRAM;
static int32_t decoded4[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_XLARGE_IRAM;
static int32_t decoded5[MAX_BLOCKSIZE] IBSS_ATTR_FLAC_XLARGE_IRAM;
#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 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;
uint16_t blocksize;
};
static struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
static int nseekpoints;
static int8_t *bit_buffer;
static size_t buff_size;
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;
uint16_t blocksize;
int endofmetadata=0;
uint32_t blocklength;
ci->memset(fc,0,sizeof(FLACContext));
nseekpoints=0;
fc->sample_skip = 0;
/* Reset sample buffers */
memset(decoded0, 0, sizeof(decoded0));
memset(decoded1, 0, sizeof(decoded1));
memset(decoded2, 0, sizeof(decoded2));
memset(decoded3, 0, sizeof(decoded3));
memset(decoded4, 0, sizeof(decoded4));
memset(decoded5, 0, sizeof(decoded5));
/* Set sample buffers in decoder structure */
fc->decoded[0] = decoded0;
fc->decoded[1] = decoded1;
fc->decoded[2] = decoded2;
fc->decoded[3] = decoded3;
fc->decoded[4] = decoded4;
fc->decoded[5] = decoded5;
/* 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 */
{
if (ci->read_filebuf(buf, blocklength) < blocklength) return false;
fc->filesize = ci->filesize;
fc->min_blocksize = (buf[0] << 8) | buf[1];
int max_blocksize = (buf[2] << 8) | buf[3];
if (max_blocksize > MAX_BLOCKSIZE)
{
LOGF("FLAC: Maximum blocksize is too large (%d > %d)\n",
max_blocksize, MAX_BLOCKSIZE);
return false;
}
fc->max_blocksize = max_blocksize;
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 = ((int64_t) fc->totalsamples * 1000) / fc->samplerate;
found_streaminfo=true;
} else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
(blocklength >= 18)) {
if (ci->read_filebuf(buf,18) < 18) return false;
blocklength-=18;
seekpoint_hi=(buf[0] << 24) | (buf[1] << 16) |
(buf[2] << 8) | buf[3];
seekpoint_lo=(buf[4] << 24) | (buf[5] << 16) |
(buf[6] << 8) | buf[7];
offset_hi=(buf[8] << 24) | (buf[9] << 16) |
(buf[10] << 8) | buf[11];
offset_lo=(buf[12] << 24) | (buf[13] << 16) |
(buf[14] << 8) | buf[15];
blocksize=(buf[16] << 8) | buf[17];
/* Only store seekpoints where the high 32 bits are zero */
if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
(offset_hi == 0)) {
seekpoints[nseekpoints].sample=seekpoint_lo;
seekpoints[nseekpoints].offset=offset_lo;
seekpoints[nseekpoints].blocksize=blocksize;
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 = ((int64_t) (fc->filesize-fc->metadatalength) * 8)
/ fc->length;
return true;
} else {
return false;
}
}
/* Synchronize to next frame in stream - adapted from libFLAC 1.1.3b2 */
static bool frame_sync(FLACContext* fc) {
unsigned int x = 0;
bool cached = false;
/* Make sure we're byte aligned. */
align_get_bits(&fc->gb);
while(1) {
if(fc->gb.size_in_bits - get_bits_count(&fc->gb) < 8) {
/* Error, end of bitstream, a valid stream should never reach here
* since the buffer should contain at least one frame header.
*/
return false;
}
if(cached)
cached = false;
else
x = get_bits(&fc->gb, 8);
if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
x = get_bits(&fc->gb, 8);
/* We have to check if we just read two 0xff's in a row; the second
* may actually be the beginning of the sync code.
*/
if(x == 0xff) { /* MAGIC NUMBER for first 8 frame sync bits. */
cached = true;
}
else if(x >> 2 == 0x3e) { /* MAGIC NUMBER for last 6 sync bits. */
/* Succesfully synced. */
break;
}
}
}
/* Advance and init bit buffer to the new frame. */
ci->advance_buffer((get_bits_count(&fc->gb)-16)>>3); /* consumed bytes */
bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
init_get_bits(&fc->gb, bit_buffer, buff_size*8);
/* Decode the frame to verify the frame crc and
* fill fc with its metadata.
*/
if(flac_decode_frame(fc,
bit_buffer, buff_size, ci->yield) < 0) {
return false;
}
return true;
}
/* Seek to sample - adapted from libFLAC 1.1.3b2+ */
static bool flac_seek(FLACContext* fc, uint32_t target_sample) {
off_t orig_pos = ci->curpos;
off_t pos = -1;
unsigned long lower_bound, upper_bound;
unsigned long lower_bound_sample, upper_bound_sample;
int i;
unsigned approx_bytes_per_frame;
uint32_t this_frame_sample = fc->samplenumber;
unsigned this_block_size = fc->blocksize;
bool needs_seek = true, first_seek = true;
/* We are just guessing here. */
if(fc->max_framesize > 0)
approx_bytes_per_frame = (fc->max_framesize + fc->min_framesize)/2 + 1;
/* Check if it's a known fixed-blocksize stream. */
else if(fc->min_blocksize == fc->max_blocksize && fc->min_blocksize > 0)
approx_bytes_per_frame = fc->min_blocksize*fc->channels*fc->bps/8 + 64;
else
approx_bytes_per_frame = 4608 * fc->channels * fc->bps/8 + 64;
/* Set an upper and lower bound on where in the stream we will search. */
lower_bound = fc->metadatalength;
lower_bound_sample = 0;
upper_bound = fc->filesize;
upper_bound_sample = fc->totalsamples>0 ? fc->totalsamples : target_sample;
/* Refine the bounds if we have a seektable with suitable points. */
if(nseekpoints > 0) {
/* Find the closest seek point <= target_sample, if it exists. */
for(i = nseekpoints-1; i >= 0; i--) {
if(seekpoints[i].sample <= target_sample)
break;
}
if(i >= 0) { /* i.e. we found a suitable seek point... */
lower_bound = fc->metadatalength + seekpoints[i].offset;
lower_bound_sample = seekpoints[i].sample;
}
/* Find the closest seek point > target_sample, if it exists. */
for(i = 0; i < nseekpoints; i++) {
if(seekpoints[i].sample > target_sample)
break;
}
if(i < nseekpoints) { /* i.e. we found a suitable seek point... */
upper_bound = fc->metadatalength + seekpoints[i].offset;
upper_bound_sample = seekpoints[i].sample;
}
}
while(1) {
/* Check if bounds are still ok. */
if(lower_bound_sample >= upper_bound_sample ||
lower_bound > upper_bound) {
return false;
}
/* Calculate new seek position */
if(needs_seek) {
pos = (off_t)(lower_bound +
(((target_sample - lower_bound_sample) *
(int64_t)(upper_bound - lower_bound)) /
(upper_bound_sample - lower_bound_sample)) -
approx_bytes_per_frame);
if(pos >= (off_t)upper_bound)
pos = (off_t)upper_bound-1;
if(pos < (off_t)lower_bound)
pos = (off_t)lower_bound;
}
if(!ci->seek_buffer(pos))
return false;
bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE+16);
init_get_bits(&fc->gb, bit_buffer, buff_size*8);
/* Now we need to get a frame. It is possible for our seek
* to land in the middle of audio data that looks exactly like
* a frame header from a future version of an encoder. When
* that happens, frame_sync() will return false.
* But there is a remote possibility that it is properly
* synced at such a "future-codec frame", so to make sure,
* we wait to see several "unparseable" errors in a row before
* bailing out.
*/
{
unsigned unparseable_count;
bool got_a_frame = false;
for(unparseable_count = 0; !got_a_frame
&& unparseable_count < 30; unparseable_count++) {
if(frame_sync(fc))
got_a_frame = true;
}
if(!got_a_frame) {
ci->seek_buffer(orig_pos);
return false;
}
}
this_frame_sample = fc->samplenumber;
this_block_size = fc->blocksize;
if(target_sample >= this_frame_sample
&& target_sample < this_frame_sample+this_block_size) {
/* Found the frame containing the target sample. */
fc->sample_skip = target_sample - this_frame_sample;
break;
}
if(this_frame_sample + this_block_size >= upper_bound_sample &&
!first_seek) {
if(pos == (off_t)lower_bound || !needs_seek) {
ci->seek_buffer(orig_pos);
return false;
}
/* Our last move backwards wasn't big enough, try again. */
approx_bytes_per_frame *= 2;
continue;
}
/* Allow one seek over upper bound,
* required for streams with unknown total samples.
*/
first_seek = false;
/* Make sure we are not seeking in a corrupted stream */
if(this_frame_sample < lower_bound_sample) {
ci->seek_buffer(orig_pos);
return false;
}
approx_bytes_per_frame = this_block_size*fc->channels*fc->bps/8 + 64;
/* We need to narrow the search. */
if(target_sample < this_frame_sample) {
upper_bound_sample = this_frame_sample;
upper_bound = ci->curpos;
}
else { /* Target is beyond this frame. */
/* We are close, continue in decoding next frames. */
if(target_sample < this_frame_sample + 4*this_block_size) {
pos = ci->curpos + fc->framesize;
needs_seek = false;
}
lower_bound_sample = this_frame_sample + this_block_size;
lower_bound = ci->curpos + fc->framesize;
}
}
return true;
}
/* Seek to file offset */
static bool flac_seek_offset(FLACContext* fc, uint32_t offset) {
unsigned unparseable_count;
bool got_a_frame = false;
if(!ci->seek_buffer(offset))
return false;
bit_buffer = ci->request_buffer(&buff_size, MAX_FRAMESIZE);
init_get_bits(&fc->gb, bit_buffer, buff_size*8);
for(unparseable_count = 0; !got_a_frame
&& unparseable_count < 10; unparseable_count++) {
if(frame_sync(fc))
got_a_frame = true;
}
if(!got_a_frame) {
ci->seek_buffer(fc->metadatalength);
return false;
}
return true;
}
/* this is the codec entry point */
enum codec_status codec_main(enum codec_entry_call_reason reason)
{
if (reason == CODEC_LOAD) {
/* Generic codec initialisation */
ci->configure(DSP_SET_SAMPLE_DEPTH, FLAC_OUTPUT_DEPTH-1);
}
return CODEC_OK;
}
/* this is called for each file to process */
enum codec_status codec_run(void)
{
int8_t *buf;
uint32_t samplesdone;
uint32_t elapsedtime;
size_t bytesleft;
int consumed;
int res;
int frame;
intptr_t param;
if (codec_init()) {
LOGF("FLAC: Error initialising codec\n");
return CODEC_ERROR;
}
/* Need to save offset for later use (cleared indirectly by flac_init) */
samplesdone = ci->id3->offset;
if (!flac_init(&fc,ci->id3->first_frame_offset)) {
LOGF("FLAC: Error initialising codec\n");
return CODEC_ERROR;
}
ci->configure(DSP_SET_FREQUENCY, ci->id3->frequency);
ci->configure(DSP_SET_STEREO_MODE, fc.channels == 1 ?
STEREO_MONO : STEREO_NONINTERLEAVED);
codec_set_replaygain(ci->id3);
flac_seek_offset(&fc, samplesdone);
samplesdone=fc.samplenumber+fc.blocksize;
elapsedtime=((uint64_t)samplesdone*1000)/(ci->id3->frequency);
ci->set_elapsed(elapsedtime);
/* The main decoding loop */
frame=0;
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
while (bytesleft) {
enum codec_command_action action = ci->get_command(&param);
if (action == CODEC_ACTION_HALT)
break;
/* Deal with any pending seek requests */
if (action == CODEC_ACTION_SEEK_TIME) {
if (flac_seek(&fc,(uint32_t)(((uint64_t)param
*ci->id3->frequency)/1000))) {
/* Refill the input buffer */
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
}
ci->set_elapsed(param);
ci->seek_complete();
}
if((res=flac_decode_frame(&fc,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();
ci->pcmbuf_insert(&fc.decoded[0][fc.sample_skip], &fc.decoded[1][fc.sample_skip],
fc.blocksize - fc.sample_skip);
fc.sample_skip = 0;
/* Update the elapsed-time indicator */
samplesdone=fc.samplenumber+fc.blocksize;
elapsedtime=((uint64_t)samplesdone*1000)/(ci->id3->frequency);
ci->set_elapsed(elapsedtime);
ci->advance_buffer(consumed);
buf = ci->request_buffer(&bytesleft, MAX_FRAMESIZE);
}
LOGF("FLAC: Decoded %lu samples\n",(unsigned long)samplesdone);
return CODEC_OK;
}
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