Initial seeking support. This only seeks to the nearest point (before the target sample) in the seektable. NOTE: not all FLAC files have seektables - some front-ends have the skill to create FLAC files without them. You can add seek points every 10 seconds to a FLAC file with the command: metaflac --add-seekpoint=10s file.flac
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7680 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Dave Chapman
parent
d452d26885
commit
dff9352430
1 changed files with 106 additions and 10 deletions
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@ -33,14 +33,59 @@ struct codec_api* ci;
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int32_t decoded0[MAX_BLOCKSIZE] IBSS_ATTR;
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int32_t decoded1[MAX_BLOCKSIZE] IBSS_ATTR;
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#define MAX_SUPPORTED_SEEKTABLE_SIZE 5000
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/* Notes about seeking:
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The full seek table consists of:
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uint64_t sample (only 36 bits are used)
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uint64_t offset
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uint32_t blocksize
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We don't store the blocksize (of the target frame) and we also
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limit the sample and offset values to 32-bits - Rockbox doesn't support
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files bigger than 2GB on FAT32 filesystems.
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The reference FLAC encoder produces a seek table with points every
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10 seconds, but this can be overridden by the user when encoding a file.
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With the default settings, a typical 4 minute track will contain
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24 seek points.
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Taking the extreme case of a Rockbox supported file to be a 2GB (compressed)
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16-bit/44.1KHz mono stream with a likely uncompressed size of 4GB:
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Total duration is: 48694 seconds (about 810 minutes - 13.5 hours)
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Total number of seek points: 4869
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Therefore we limit the number of seek points to 5000. This is a
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very extreme case, and requires 5000*8=40000 bytes of storage.
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If we come across a FLAC file with more than this number of seekpoints, we
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just use the first 5000.
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*/
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struct FLACseekpoints {
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uint32_t sample;
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uint32_t offset;
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};
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struct FLACseekpoints seekpoints[MAX_SUPPORTED_SEEKTABLE_SIZE];
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int nseekpoints;
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static bool flac_init(FLACContext* fc)
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{
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unsigned char buf[255];
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bool found_streaminfo=false;
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uint32_t seekpoint_hi,seekpoint_lo;
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uint32_t offset_hi,offset_lo;
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int endofmetadata=0;
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int blocklength;
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int n;
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uint32_t* p;
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ci->memset(fc,0,sizeof(FLACContext));
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nseekpoints=0;
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if (ci->read_filebuf(buf, 4) < 4)
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{
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@ -92,7 +137,28 @@ static bool flac_init(FLACContext* fc)
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found_streaminfo=true;
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} else if ((buf[0] & 0x7f) == 3) { /* 3 is the SEEKTABLE block */
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ci->advance_buffer(blocklength);
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while ((nseekpoints < MAX_SUPPORTED_SEEKTABLE_SIZE) &&
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(blocklength >= 18)) {
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n=ci->read_filebuf(buf,18);
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if (n < 18) return false;
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blocklength-=n;
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p=(uint32_t*)buf;
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seekpoint_hi=betoh32(*(p++));
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seekpoint_lo=betoh32(*(p++));
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offset_hi=betoh32(*(p++));
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offset_lo=betoh32(*(p++));
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if ((seekpoint_hi == 0) && (seekpoint_lo != 0xffffffff) &&
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(offset_hi == 0)) {
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seekpoints[nseekpoints].sample=seekpoint_lo;
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seekpoints[nseekpoints].offset=offset_lo;
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nseekpoints++;
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}
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}
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/* Skip any unread seekpoints */
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if (blocklength > 0)
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ci->advance_buffer(blocklength);
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} else {
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/* Skip to next metadata block */
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ci->advance_buffer(blocklength);
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@ -107,6 +173,40 @@ static bool flac_init(FLACContext* fc)
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}
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}
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/* A very simple seek implementation - seek to the seekpoint before
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the target sample.
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This needs to be improved to seek with greater accuracy
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*/
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bool flac_seek(FLACContext* fc, uint32_t newsample) {
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uint32_t offset;
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int i;
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if (nseekpoints==0) {
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offset=0;
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} else {
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i=nseekpoints-1;
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while ((i > 0) && (seekpoints[i].sample > newsample)) {
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i--;
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}
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if ((i==0) && (seekpoints[i].sample > newsample)) {
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offset=0;
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} else {
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offset=seekpoints[i].offset;
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}
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}
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offset+=fc->metadatalength;
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if ((off_t)offset < ci->filesize) {
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ci->seek_buffer(offset);
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return true;
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} else {
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return false;
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}
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}
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/* this is the codec entry point */
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enum codec_status codec_start(struct codec_api* api)
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{
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@ -163,15 +263,11 @@ enum codec_status codec_start(struct codec_api* api)
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/* Deal with any pending seek requests */
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if (ci->seek_time) {
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/* We only support seeking to start of track at the moment */
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if (ci->seek_time==1) {
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if (ci->seek_buffer(fc.metadatalength)) {
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/* Refill the input buffer */
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bytesleft=ci->read_filebuf(buf,sizeof(buf));
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ci->set_elapsed(0);
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}
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}
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ci->seek_time = 0;
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if (flac_seek(&fc,(ci->seek_time/20) * (ci->id3->frequency/50))) {
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/* Refill the input buffer */
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bytesleft=ci->read_filebuf(buf,sizeof(buf));
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}
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ci->seek_time = 0;
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}
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if((res=flac_decode_frame(&fc,decoded0,decoded1,buf,
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