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@ -15,18 +15,20 @@ |
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//
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// Limitations:
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//
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// - seeking not supported except manually via PUSHDATA api
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// - floor 0 not supported (used in old ogg vorbis files pre-2004)
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// - lossless sample-truncation at beginning ignored
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// - cannot concatenate multiple vorbis streams
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// - sample positions are 32-bit, limiting seekable 192Khz
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// files to around 6 hours (Ogg supports 64-bit)
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//
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// Feature contributors:
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// Dougall Johnson (sample-exact seeking)
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//
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// Bugfix/warning contributors:
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// Terje Mathisen Niklas Frykholm Andy Hill
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// Casey Muratori John Bolton Gargaj
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// Laurent Gomila Marc LeBlanc Ronny Chevalier
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// Bernhard Wodo Evan Balster "alxprd"@github
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// Bernhard Wodo Evan Balster "alxprd"@github
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// Tom Beaumont Ingo Leitgeb Nicolas Guillemot
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// (If you reported a bug but do not appear in this list, it is because
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// someone else reported the bug before you. There were too many of you to
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@ -259,7 +261,6 @@ extern stb_vorbis * stb_vorbis_open_file_section(FILE *f, int close_handle_on_cl |
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extern int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number); |
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extern int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number); |
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// NOT WORKING YET
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// these functions seek in the Vorbis file to (approximately) 'sample_number'.
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// after calling seek_frame(), the next call to get_frame_*() will include
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// the specified sample. after calling stb_vorbis_seek(), the next call to
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@ -268,8 +269,7 @@ extern int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number); |
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// you can also use seek_frame().
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extern void stb_vorbis_seek_start(stb_vorbis *f); |
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// this function is equivalent to stb_vorbis_seek(f,0), but it
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// actually works
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// this function is equivalent to stb_vorbis_seek(f,0)
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extern unsigned int stb_vorbis_stream_length_in_samples(stb_vorbis *f); |
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extern float stb_vorbis_stream_length_in_seconds(stb_vorbis *f); |
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@ -714,8 +714,6 @@ typedef struct |
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typedef struct |
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{ |
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uint32 page_start, page_end; |
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uint32 after_previous_page_start; |
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uint32 first_decoded_sample; |
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uint32 last_decoded_sample; |
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} ProbedPage; |
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@ -1423,8 +1421,6 @@ static int start_page_no_capturepattern(vorb *f) |
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len += 27 + f->segment_count; |
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p.page_start = f->first_audio_page_offset; |
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p.page_end = p.page_start + len; |
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p.after_previous_page_start = p.page_start; |
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p.first_decoded_sample = 0; |
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p.last_decoded_sample = loc0; |
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f->p_first = p; |
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} |
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@ -4470,7 +4466,7 @@ static uint32 vorbis_find_page(stb_vorbis *f, uint32 *end, uint32 *last) |
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int n; |
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if (f->eof) return 0; |
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n = get8(f); |
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if (n == 0x4f) { // page header
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if (n == 0x4f) { // page header candidate
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unsigned int retry_loc = stb_vorbis_get_file_offset(f); |
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int i; |
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// check if we're off the end of a file_section stream
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@ -4534,37 +4530,30 @@ static uint32 vorbis_find_page(stb_vorbis *f, uint32 *end, uint32 *last) |
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} |
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} |
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// seek is implemented with 'interpolation search'--this is like
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// binary search, but we use the data values to estimate the likely
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// location of the data item (plus a bit of a bias so when the
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// estimation is wrong we don't waste overly much time)
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#define SAMPLE_unknown 0xffffffff |
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// seeking is implemented with a binary search, which narrows down the range to
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// 64K, before using a linear search (because finding the synchronization
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// pattern can be expensive, and the chance we'd find the end page again is
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// relatively high for small ranges)
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//
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// two initial interpolation-style probes are used at the start of the search
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// to try to bound either side of the binary search sensibly, while still
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// working in O(log n) time if they fail.
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// ogg vorbis, in its insane infinite wisdom, only provides
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// information about the sample at the END of the page.
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// therefore we COULD have the data we need in the current
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// page, and not know it. we could just use the end location
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// as our only knowledge for bounds, seek back, and eventually
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// the binary search finds it. or we can try to be smart and
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// not waste time trying to locate more pages. we try to be
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// smart, since this data is already in memory anyway, so
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// doing needless I/O would be crazy!
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static int vorbis_analyze_page(stb_vorbis *f, ProbedPage *z) |
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static int get_seek_page_info(stb_vorbis *f, ProbedPage *z) |
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{ |
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uint8 header[27], lacing[255]; |
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uint8 packet_type[255]; |
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int num_packet, packet_start; |
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int i,len; |
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uint32 samples; |
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// record where the page starts
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z->page_start = stb_vorbis_get_file_offset(f); |
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// parse the header
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getn(f, header, 27); |
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assert(header[0] == 'O' && header[1] == 'g' && header[2] == 'g' && header[3] == 'S'); |
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if (header[0] != 'O' || header[1] != 'g' || header[2] != 'g' || header[3] != 'S') |
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return 0; |
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getn(f, lacing, header[26]); |
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// determine the length of the payload
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@ -4576,304 +4565,265 @@ static int vorbis_analyze_page(stb_vorbis *f, ProbedPage *z) |
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z->page_end = z->page_start + 27 + header[26] + len; |
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// read the last-decoded sample out of the data
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z->last_decoded_sample = header[6] + (header[7] << 8) + (header[8] << 16) + (header[9] << 16); |
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z->last_decoded_sample = header[6] + (header[7] << 8) + (header[8] << 16) + (header[9] << 24); |
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if (header[5] & 4) { |
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// if this is the last page, it's not possible to work
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// backwards to figure out the first sample! whoops! fuck.
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z->first_decoded_sample = SAMPLE_unknown; |
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set_file_offset(f, z->page_start); |
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return 1; |
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} |
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// restore file state to where we were
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set_file_offset(f, z->page_start); |
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return 1; |
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} |
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// scan through the frames to determine the sample-count of each one...
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// our goal is the sample # of the first fully-decoded sample on the
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// page, which is the first decoded sample of the 2nd packet
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// rarely used function to seek back to the preceeding page while finding the
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// start of a packet
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static int go_to_page_before(stb_vorbis *f, unsigned int limit_offset) |
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{ |
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unsigned int previous_safe, end; |
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num_packet=0; |
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// now we want to seek back 64K from the limit
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if (limit_offset >= 65536 && limit_offset-65536 >= f->first_audio_page_offset) |
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previous_safe = limit_offset - 65536; |
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else |
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previous_safe = f->first_audio_page_offset; |
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packet_start = ((header[5] & 1) == 0); |
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set_file_offset(f, previous_safe); |
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for (i=0; i < header[26]; ++i) { |
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if (packet_start) { |
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uint8 n,b; |
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if (lacing[i] == 0) goto bail; // trying to read from zero-length packet
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n = get8(f); |
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// if bottom bit is non-zero, we've got corruption
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if (n & 1) goto bail; |
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n >>= 1; |
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b = ilog(f->mode_count-1); |
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n &= (1 << b)-1; |
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if (n >= f->mode_count) goto bail; |
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packet_type[num_packet++] = f->mode_config[n].blockflag; |
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skip(f, lacing[i]-1); |
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} else |
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skip(f, lacing[i]); |
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packet_start = (lacing[i] < 255); |
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} |
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// now that we know the sizes of all the pages, we can start determining
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// how much sample data there is.
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samples = 0; |
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// for the last packet, we step by its whole length, because the definition
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// is that we encoded the end sample loc of the 'last packet completed',
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// where 'completed' refers to packets being split, and we are left to guess
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// what 'end sample loc' means. we assume it means ignoring the fact that
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// the last half of the data is useless without windowing against the next
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// packet... (so it's not REALLY complete in that sense)
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if (num_packet > 1) |
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samples += f->blocksize[packet_type[num_packet-1]]; |
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for (i=num_packet-2; i >= 1; --i) { |
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// now, for this packet, how many samples do we have that
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// do not overlap the following packet?
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if (packet_type[i] == 1) |
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if (packet_type[i+1] == 1) |
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samples += f->blocksize_1 >> 1; |
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else |
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samples += ((f->blocksize_1 - f->blocksize_0) >> 2) + (f->blocksize_0 >> 1); |
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else |
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samples += f->blocksize_0 >> 1; |
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} |
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// now, at this point, we've rewound to the very beginning of the
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// _second_ packet. if we entirely discard the first packet after
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// a seek, this will be exactly the right sample number. HOWEVER!
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// we can't as easily compute this number for the LAST page. The
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// only way to get the sample offset of the LAST page is to use
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// the end loc from the previous page. But what that returns us
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// is _exactly_ the place where we get our first non-overlapped
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// sample. (I think. Stupid spec for being ambiguous.) So for
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// consistency it's better to do that here, too. However, that
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// will then require us to NOT discard all of the first frame we
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// decode, in some cases, which means an even weirder frame size
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// and extra code. what a fucking pain.
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// we're going to discard the first packet if we
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// start the seek here, so we don't care about it. (we could actually
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// do better; if the first packet is long, and the previous packet
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// is short, there's actually data in the first half of the first
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// packet that doesn't need discarding... but not worth paying the
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// effort of tracking that of that here and in the seeking logic)
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// except crap, if we infer it from the _previous_ packet's end
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// location, we DO need to use that definition... and we HAVE to
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// infer the start loc of the LAST packet from the previous packet's
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// end location. fuck you, ogg vorbis.
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z->first_decoded_sample = z->last_decoded_sample - samples; |
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// restore file state to where we were
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set_file_offset(f, z->page_start); |
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return 1; |
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while (vorbis_find_page(f, &end, NULL)) { |
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if (end >= limit_offset && stb_vorbis_get_file_offset(f) < limit_offset) |
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return 1; |
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set_file_offset(f, end); |
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} |
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// restore file state to where we were
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bail: |
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set_file_offset(f, z->page_start); |
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return 0; |
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} |
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static int vorbis_seek_frame_from_page(stb_vorbis *f, uint32 page_start, uint32 first_sample, uint32 target_sample, int fine) |
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{ |
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int left_start, left_end, right_start, right_end, mode,i; |
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int frame=0; |
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uint32 frame_start; |
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int frames_to_skip, data_to_skip; |
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// implements the search logic for finding a page and starting decoding. if
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// the function succeeds, current_loc_valid will be true and current_loc will
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// be less than or equal to the provided sample number (the closer the
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// better).
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static int seek_to_sample_coarse(stb_vorbis *f, uint32 sample_number) |
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{ |
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ProbedPage left, right, mid; |
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int i, start_seg_with_known_loc, end_pos, page_start; |
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uint32 delta, stream_length, padding; |
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double offset, bytes_per_sample; |
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int probe = 0; |
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// find the last page and validate the target sample
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stream_length = stb_vorbis_stream_length_in_samples(f); |
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if (stream_length == 0) return error(f, VORBIS_seek_without_length); |
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if (sample_number > stream_length) return error(f, VORBIS_seek_invalid); |
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// this is the maximum difference between the window-center (which is the
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// actual granule position value), and the right-start (which the spec
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// indicates should be the granule position (give or take one)).
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padding = ((f->blocksize_1 - f->blocksize_0) >> 2); |
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if (sample_number < padding) |
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sample_number = 0; |
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else |
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sample_number -= padding; |
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// first_sample is the sample # of the first sample that doesn't
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// overlap the previous page... note that this requires us to
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// _partially_ discard the first packet! bleh.
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set_file_offset(f, page_start); |
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left = f->p_first; |
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while (left.last_decoded_sample == ~0U) { |
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// (untested) the first page does not have a 'last_decoded_sample'
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set_file_offset(f, left.page_end); |
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if (!get_seek_page_info(f, &left)) goto error; |
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} |
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f->next_seg = -1; // force page resync
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right = f->p_last; |
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assert(right.last_decoded_sample != ~0U); |
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frame_start = first_sample; |
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// frame start is where the previous packet's last decoded sample
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// was, which corresponds to left_end... EXCEPT if the previous
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// packet was long and this packet is short? Probably a bug here.
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// starting from the start is handled differently
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if (sample_number <= left.last_decoded_sample) { |
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stb_vorbis_seek_start(f); |
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return 1; |
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} |
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while (left.page_end != right.page_start) { |
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assert(left.page_end < right.page_start); |
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// search range in bytes
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delta = right.page_start - left.page_end; |
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|
|
if (delta <= 65536) { |
|
|
|
|
// there's only 64K left to search - handle it linearly
|
|
|
|
|
set_file_offset(f, left.page_end); |
|
|
|
|
} else { |
|
|
|
|
if (probe < 2) { |
|
|
|
|
if (probe == 0) { |
|
|
|
|
// first probe (interpolate)
|
|
|
|
|
double data_bytes = right.page_end - left.page_start; |
|
|
|
|
bytes_per_sample = data_bytes / right.last_decoded_sample; |
|
|
|
|
offset = left.page_start + bytes_per_sample * (sample_number - left.last_decoded_sample); |
|
|
|
|
} else { |
|
|
|
|
// second probe (try to bound the other side)
|
|
|
|
|
double error = ((double) sample_number - mid.last_decoded_sample) * bytes_per_sample; |
|
|
|
|
if (error >= 0 && error < 8000) error = 8000; |
|
|
|
|
if (error < 0 && error > -8000) error = -8000; |
|
|
|
|
offset += error * 2; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
// now, we can start decoding frames... we'll only FAKE decode them,
|
|
|
|
|
// until we find the frame that contains our sample; then we'll rewind,
|
|
|
|
|
// and try again
|
|
|
|
|
for (;;) { |
|
|
|
|
int start; |
|
|
|
|
// ensure the offset is valid
|
|
|
|
|
if (offset < left.page_end) |
|
|
|
|
offset = left.page_end; |
|
|
|
|
if (offset > right.page_start - 65536) |
|
|
|
|
offset = right.page_start - 65536; |
|
|
|
|
|
|
|
|
|
if (!vorbis_decode_initial(f, &left_start, &left_end, &right_start, &right_end, &mode)) |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
set_file_offset(f, (unsigned int) offset); |
|
|
|
|
} else { |
|
|
|
|
// binary search for large ranges (offset by 32K to ensure
|
|
|
|
|
// we don't hit the right page)
|
|
|
|
|
set_file_offset(f, left.page_end + (delta / 2) - 32768); |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
if (frame == 0) |
|
|
|
|
start = left_end; |
|
|
|
|
else |
|
|
|
|
start = left_start; |
|
|
|
|
if (!vorbis_find_page(f, NULL, NULL)) goto error; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
// the window starts at left_start; the last valid sample we generate
|
|
|
|
|
// before the next frame's window start is right_start-1
|
|
|
|
|
if (target_sample < frame_start + right_start-start) |
|
|
|
|
break; |
|
|
|
|
for (;;) { |
|
|
|
|
if (!get_seek_page_info(f, &mid)) goto error; |
|
|
|
|
if (mid.last_decoded_sample != ~0U) break; |
|
|
|
|
// (untested) no frames end on this page
|
|
|
|
|
set_file_offset(f, mid.page_end); |
|
|
|
|
assert(mid.page_start < right.page_start); |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
flush_packet(f); |
|
|
|
|
if (f->eof) |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
// if we've just found the last page again then we're in a tricky file,
|
|
|
|
|
// and we're close enough.
|
|
|
|
|
if (mid.page_start == right.page_start) |
|
|
|
|
break; |
|
|
|
|
|
|
|
|
|
frame_start += right_start - start; |
|
|
|
|
if (sample_number < mid.last_decoded_sample) |
|
|
|
|
right = mid; |
|
|
|
|
else |
|
|
|
|
left = mid; |
|
|
|
|
|
|
|
|
|
++frame; |
|
|
|
|
++probe; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
// ok, at this point, the sample we want is contained in frame #'frame'
|
|
|
|
|
// seek back to start of the last packet
|
|
|
|
|
page_start = left.page_start; |
|
|
|
|
set_file_offset(f, page_start); |
|
|
|
|
if (!start_page(f)) return error(f, VORBIS_seek_failed); |
|
|
|
|
end_pos = f->end_seg_with_known_loc; |
|
|
|
|
assert(end_pos >= 0); |
|
|
|
|
|
|
|
|
|
// to decode frame #'frame' normally, we have to decode the
|
|
|
|
|
// previous frame first... but if it's the FIRST frame of the page
|
|
|
|
|
// we can't. if it's the first frame, it means it falls in the part
|
|
|
|
|
// of the first frame that doesn't overlap either of the other frames.
|
|
|
|
|
// so, if we have to handle that case for the first frame, we might
|
|
|
|
|
// as well handle it for all of them, so:
|
|
|
|
|
if (target_sample > frame_start + (left_end - left_start)) { |
|
|
|
|
// so what we want to do is go ahead and just immediately decode
|
|
|
|
|
// this frame, but then make it so the next get_frame_float() uses
|
|
|
|
|
// this already-decoded data? or do we want to go ahead and rewind,
|
|
|
|
|
// and leave a flag saying to skip the first N data? let's do that
|
|
|
|
|
frames_to_skip = frame; // if this is frame #1, skip 1 frame (#0)
|
|
|
|
|
data_to_skip = left_end - left_start; |
|
|
|
|
} else { |
|
|
|
|
// otherwise, we want to skip frames 0, 1, 2, ... frame-2
|
|
|
|
|
// (which means frame-2+1 total frames) then decode frame-1,
|
|
|
|
|
// then leave frame pending
|
|
|
|
|
frames_to_skip = frame - 1; |
|
|
|
|
assert(frames_to_skip >= 0); |
|
|
|
|
data_to_skip = -1;
|
|
|
|
|
} |
|
|
|
|
for (;;) { |
|
|
|
|
for (i = end_pos; i > 0; --i) |
|
|
|
|
if (f->segments[i-1] != 255) |
|
|
|
|
break; |
|
|
|
|
|
|
|
|
|
set_file_offset(f, page_start); |
|
|
|
|
f->next_seg = - 1; // force page resync
|
|
|
|
|
start_seg_with_known_loc = i; |
|
|
|
|
|
|
|
|
|
for (i=0; i < frames_to_skip; ++i) { |
|
|
|
|
maybe_start_packet(f); |
|
|
|
|
flush_packet(f); |
|
|
|
|
} |
|
|
|
|
if (start_seg_with_known_loc > 0 || !(f->page_flag & PAGEFLAG_continued_packet)) |
|
|
|
|
break; |
|
|
|
|
|
|
|
|
|
if (data_to_skip >= 0) { |
|
|
|
|
int i,j,n = f->blocksize_0 >> 1; |
|
|
|
|
f->discard_samples_deferred = data_to_skip; |
|
|
|
|
for (i=0; i < f->channels; ++i) |
|
|
|
|
for (j=0; j < n; ++j) |
|
|
|
|
f->previous_window[i][j] = 0; |
|
|
|
|
f->previous_length = n; |
|
|
|
|
frame_start += data_to_skip; |
|
|
|
|
} else { |
|
|
|
|
f->previous_length = 0; |
|
|
|
|
vorbis_pump_first_frame(f); |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
// at this point, the NEXT decoded frame will generate the desired sample
|
|
|
|
|
if (fine) { |
|
|
|
|
// so if we're doing sample accurate streaming, we want to go ahead and decode it!
|
|
|
|
|
if (target_sample != frame_start) { |
|
|
|
|
int n; |
|
|
|
|
stb_vorbis_get_frame_float(f, &n, NULL); |
|
|
|
|
assert(target_sample > frame_start); |
|
|
|
|
assert(f->channel_buffer_start + (int) (target_sample-frame_start) < f->channel_buffer_end); |
|
|
|
|
f->channel_buffer_start += (target_sample - frame_start); |
|
|
|
|
} |
|
|
|
|
// (untested) the final packet begins on an earlier page
|
|
|
|
|
if (!go_to_page_before(f, page_start)) |
|
|
|
|
goto error; |
|
|
|
|
|
|
|
|
|
page_start = stb_vorbis_get_file_offset(f); |
|
|
|
|
if (!start_page(f)) goto error; |
|
|
|
|
end_pos = f->segment_count - 1; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
return 0; |
|
|
|
|
// prepare to start decoding
|
|
|
|
|
f->current_loc_valid = FALSE; |
|
|
|
|
f->last_seg = FALSE; |
|
|
|
|
f->valid_bits = 0; |
|
|
|
|
f->packet_bytes = 0; |
|
|
|
|
f->bytes_in_seg = 0; |
|
|
|
|
f->previous_length = 0; |
|
|
|
|
f->next_seg = start_seg_with_known_loc; |
|
|
|
|
|
|
|
|
|
for (i = 0; i < start_seg_with_known_loc; i++) |
|
|
|
|
skip(f, f->segments[i]); |
|
|
|
|
|
|
|
|
|
// start decoding (optimizable - this frame is generally discarded)
|
|
|
|
|
vorbis_pump_first_frame(f); |
|
|
|
|
return 1; |
|
|
|
|
|
|
|
|
|
error: |
|
|
|
|
// try to restore the file to a valid state
|
|
|
|
|
stb_vorbis_seek_start(f); |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
static int vorbis_seek_base(stb_vorbis *f, unsigned int sample_number, int fine) |
|
|
|
|
// the same as vorbis_decode_initial, but without advancing
|
|
|
|
|
static int peek_decode_initial(vorb *f, int *p_left_start, int *p_left_end, int *p_right_start, int *p_right_end, int *mode) |
|
|
|
|
{ |
|
|
|
|
ProbedPage p[2],q; |
|
|
|
|
if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing); |
|
|
|
|
int bits_read, bytes_read; |
|
|
|
|
|
|
|
|
|
// do we know the location of the last page?
|
|
|
|
|
if (f->p_last.page_start == 0) { |
|
|
|
|
uint32 z = stb_vorbis_stream_length_in_samples(f); |
|
|
|
|
if (z == 0) return error(f, VORBIS_cant_find_last_page); |
|
|
|
|
} |
|
|
|
|
if (!vorbis_decode_initial(f, p_left_start, p_left_end, p_right_start, p_right_end, mode)) |
|
|
|
|
return 0; |
|
|
|
|
|
|
|
|
|
p[0] = f->p_first; |
|
|
|
|
p[1] = f->p_last; |
|
|
|
|
// either 1 or 2 bytes were read, figure out which so we can rewind
|
|
|
|
|
bits_read = 1 + ilog(f->mode_count-1); |
|
|
|
|
if (f->mode_config[*mode].blockflag) |
|
|
|
|
bits_read += 2; |
|
|
|
|
bytes_read = (bits_read + 7) / 8; |
|
|
|
|
|
|
|
|
|
f->bytes_in_seg += bytes_read; |
|
|
|
|
f->packet_bytes -= bytes_read; |
|
|
|
|
skip(f, -bytes_read); |
|
|
|
|
if (f->next_seg == -1) |
|
|
|
|
f->next_seg = f->segment_count - 1; |
|
|
|
|
else |
|
|
|
|
f->next_seg--; |
|
|
|
|
f->valid_bits = 0; |
|
|
|
|
|
|
|
|
|
if (sample_number >= f->p_last.last_decoded_sample) |
|
|
|
|
sample_number = f->p_last.last_decoded_sample-1; |
|
|
|
|
return 1; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
if (sample_number < f->p_first.last_decoded_sample) { |
|
|
|
|
vorbis_seek_frame_from_page(f, p[0].page_start, 0, sample_number, fine); |
|
|
|
|
return 0; |
|
|
|
|
} else { |
|
|
|
|
int attempts=0; |
|
|
|
|
while (p[0].page_end < p[1].page_start) { |
|
|
|
|
uint32 probe; |
|
|
|
|
uint32 start_offset, end_offset; |
|
|
|
|
uint32 start_sample, end_sample; |
|
|
|
|
|
|
|
|
|
// copy these into local variables so we can tweak them
|
|
|
|
|
// if any are unknown
|
|
|
|
|
start_offset = p[0].page_end; |
|
|
|
|
end_offset = p[1].after_previous_page_start; // an address known to seek to page p[1]
|
|
|
|
|
start_sample = p[0].last_decoded_sample; |
|
|
|
|
end_sample = p[1].last_decoded_sample; |
|
|
|
|
|
|
|
|
|
// currently there is no such tweaking logic needed/possible?
|
|
|
|
|
if (start_sample == SAMPLE_unknown || end_sample == SAMPLE_unknown) |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
|
|
|
|
|
// now we want to lerp between these for the target samples...
|
|
|
|
|
|
|
|
|
|
// step 1: we need to bias towards the page start...
|
|
|
|
|
if (start_offset + 4000 < end_offset) |
|
|
|
|
end_offset -= 4000; |
|
|
|
|
|
|
|
|
|
// now compute an interpolated search loc
|
|
|
|
|
probe = start_offset + (int) floor((float) (end_offset - start_offset) / (end_sample - start_sample) * (sample_number - start_sample)); |
|
|
|
|
|
|
|
|
|
// next we need to bias towards binary search...
|
|
|
|
|
// code is a little wonky to allow for full 32-bit unsigned values
|
|
|
|
|
if (attempts >= 4) { |
|
|
|
|
uint32 probe2 = start_offset + ((end_offset - start_offset) >> 1); |
|
|
|
|
if (attempts >= 8) |
|
|
|
|
probe = probe2; |
|
|
|
|
else if (probe < probe2) |
|
|
|
|
probe = probe + ((probe2 - probe) >> 1); |
|
|
|
|
else |
|
|
|
|
probe = probe2 + ((probe - probe2) >> 1); |
|
|
|
|
} |
|
|
|
|
++attempts; |
|
|
|
|
int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number) |
|
|
|
|
{ |
|
|
|
|
uint32 max_frame_samples; |
|
|
|
|
|
|
|
|
|
set_file_offset(f, probe); |
|
|
|
|
if (!vorbis_find_page(f, NULL, NULL)) return error(f, VORBIS_seek_failed); |
|
|
|
|
if (!vorbis_analyze_page(f, &q)) return error(f, VORBIS_seek_failed); |
|
|
|
|
q.after_previous_page_start = probe; |
|
|
|
|
if (IS_PUSH_MODE(f)) return error(f, VORBIS_invalid_api_mixing); |
|
|
|
|
|
|
|
|
|
// it's possible we've just found the last page again
|
|
|
|
|
if (q.page_start == p[1].page_start) { |
|
|
|
|
p[1] = q; |
|
|
|
|
continue; |
|
|
|
|
} |
|
|
|
|
// fast page-level search
|
|
|
|
|
if (!seek_to_sample_coarse(f, sample_number)) |
|
|
|
|
return 0; |
|
|
|
|
|
|
|
|
|
if (sample_number < q.last_decoded_sample) |
|
|
|
|
p[1] = q; |
|
|
|
|
else |
|
|
|
|
p[0] = q; |
|
|
|
|
} |
|
|
|
|
assert(f->current_loc_valid); |
|
|
|
|
assert(f->current_loc <= sample_number); |
|
|
|
|
|
|
|
|
|
if (p[0].last_decoded_sample <= sample_number && sample_number < p[1].last_decoded_sample) { |
|
|
|
|
vorbis_seek_frame_from_page(f, p[1].page_start, p[0].last_decoded_sample, sample_number, fine); |
|
|
|
|
return 0; |
|
|
|
|
// linear search for the relevant packet
|
|
|
|
|
max_frame_samples = (f->blocksize_1*3 - f->blocksize_0) >> 2; |
|
|
|
|
while (f->current_loc < sample_number) { |
|
|
|
|
int left_start, left_end, right_start, right_end, mode, frame_samples; |
|
|
|
|
if (!peek_decode_initial(f, &left_start, &left_end, &right_start, &right_end, &mode)) |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
// calculate the number of samples returned by the next frame
|
|
|
|
|
frame_samples = right_start - left_start; |
|
|
|
|
if (f->current_loc + frame_samples > sample_number) { |
|
|
|
|
return 1; // the next frame will contain the sample
|
|
|
|
|
} else if (f->current_loc + frame_samples + max_frame_samples > sample_number) { |
|
|
|
|
// there's a chance the frame after this could contain the sample
|
|
|
|
|
vorbis_pump_first_frame(f); |
|
|
|
|
} else { |
|
|
|
|
// this frame is too early to be relevant
|
|
|
|
|
f->current_loc += frame_samples; |
|
|
|
|
f->previous_length = 0; |
|
|
|
|
maybe_start_packet(f); |
|
|
|
|
flush_packet(f); |
|
|
|
|
} |
|
|
|
|
return error(f, VORBIS_seek_failed); |
|
|
|
|
} |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
int stb_vorbis_seek_frame(stb_vorbis *f, unsigned int sample_number) |
|
|
|
|
{ |
|
|
|
|
return vorbis_seek_base(f, sample_number, FALSE); |
|
|
|
|
// the next frame will start with the sample
|
|
|
|
|
assert(f->current_loc == sample_number); |
|
|
|
|
return 1; |
|
|
|
|
} |
|
|
|
|
|
|
|
|
|
int stb_vorbis_seek(stb_vorbis *f, unsigned int sample_number) |
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{ |
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return vorbis_seek_base(f, sample_number, TRUE); |
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if (!stb_vorbis_seek_frame(f, sample_number)) |
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return 0; |
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if (sample_number != f->current_loc) { |
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int n; |
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uint32 frame_start = f->current_loc; |
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stb_vorbis_get_frame_float(f, &n, NULL); |
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assert(sample_number > frame_start); |
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assert(f->channel_buffer_start + (int) (sample_number-frame_start) <= f->channel_buffer_end); |
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f->channel_buffer_start += (sample_number - frame_start); |
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} |
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return 1; |
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} |
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void stb_vorbis_seek_start(stb_vorbis *f) |
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@ -4954,8 +4904,6 @@ unsigned int stb_vorbis_stream_length_in_samples(stb_vorbis *f) |
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f->p_last.page_start = last_page_loc; |
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f->p_last.page_end = end; |
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f->p_last.last_decoded_sample = lo; |
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f->p_last.first_decoded_sample = SAMPLE_unknown; |
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f->p_last.after_previous_page_start = previous_safe; |
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done: |
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set_file_offset(f, restore_offset); |
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