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ogg_vorbis: Fix granule position when seeking Vorbis streams
Previously the vorbis_seek function did not take the lapped nature of Vorbis block into account when using the bisection search. Also, introduce vorbis_skip(), which can skip through packets without having to decode all the way to samples.
This commit is contained in:
Arthur Taylor
parent
ad2990ec02
commit
abe9dcc0f1
206
src/ogg_vorbis.c
206
src/ogg_vorbis.c
@ -1,4 +1,5 @@
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/*
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** Copyright (C) 2018-2021 Arthur Taylor <art@ified.ca>
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** Copyright (C) 2002-2016 Erik de Castro Lopo <erikd@mega-nerd.com>
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** Copyright (C) 2002-2005 Michael Smith <msmith@xiph.org>
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** Copyright (C) 2007 John ffitch
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@ -78,6 +79,9 @@
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#include "ogg.h"
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/* How many seconds in the future to not bother bisection searching for. */
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#define VORBIS_SEEK_THRESHOLD 2
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typedef int convert_func (SF_PRIVATE *psf, int, void *, int, int, float **) ;
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static int vorbis_read_header (SF_PRIVATE *psf) ;
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@ -85,6 +89,8 @@ static int vorbis_write_header (SF_PRIVATE *psf, int calc_length) ;
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static int vorbis_close (SF_PRIVATE *psf) ;
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static int vorbis_command (SF_PRIVATE *psf, int command, void *data, int datasize) ;
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static int vorbis_byterate (SF_PRIVATE *psf) ;
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static int vorbis_skip (SF_PRIVATE *psf, uint64_t target_gp) ;
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static int vorbis_seek_trysearch (SF_PRIVATE *psf, uint64_t target_gp) ;
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static sf_count_t vorbis_calculate_page_duration (SF_PRIVATE *psf) ;
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static sf_count_t vorbis_seek (SF_PRIVATE *psf, int mode, sf_count_t offset) ;
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static sf_count_t vorbis_read_s (SF_PRIVATE *psf, short *ptr, sf_count_t len) ;
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@ -119,22 +125,18 @@ static STR_PAIRS vorbis_metatypes [] =
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} ;
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typedef struct
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{ /* Count current location */
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sf_count_t loc ;
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{ /* Current granule position. */
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uint64_t loc ;
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/* Struct that stores all the static vorbis bitstream settings */
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vorbis_info vinfo ;
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/* Struct that stores all the bitstream user comments */
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vorbis_comment vcomment ;
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/* Ventral working state for the packet->PCM decoder */
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/* Central working state for the packet->PCM decoder */
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vorbis_dsp_state vdsp ;
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/* Local working space for packet->PCM decode */
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vorbis_block vblock ;
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/* Encoding quality in range [0.0, 1.0]. */
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double quality ;
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/* Current granule position. */
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uint64_t pcm_current ;
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/* Offset of the first samples' granule position. */
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uint64_t pcm_start ;
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/* Last valid samples' granule position. */
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@ -184,8 +186,8 @@ vorbis_read_header (SF_PRIVATE *psf)
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** Vorbis decoder.
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**
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** The next two packets in order are the comment and codebook headers.
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** They're likely large and may span multiple pages. Thus we reead
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** and submit data until we get our two pacakets, watching that no
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** They're likely large and may span multiple pages. Thus we read
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** and submit data until we get our two packets, watching that no
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** pages are missing. If a page is missing, error out ; losing a
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** header page is the only place where missing data is fatal.
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*/
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@ -231,7 +233,7 @@ vorbis_read_header (SF_PRIVATE *psf)
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psf->dataoffset = ogg_sync_ftell (psf) ;
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/*
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** Caculate the granule position offset. The first page with a payload
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** Calculate the granule position offset. The first page with a payload
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** packet shouldn't end in a continued packet. The difference between the
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** page's granule position and the sum of frames on the page tells us the
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** granule position offset.
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@ -240,7 +242,6 @@ vorbis_read_header (SF_PRIVATE *psf)
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ogg_stream_unpack_page (psf, odata) ;
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vdata->pcm_start = odata->pkt [odata->pkt_len - 1].granulepos ;
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duration = vorbis_calculate_page_duration (psf) ;
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if (duration < (sf_count_t) vdata->pcm_start)
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vdata->pcm_start -= duration ;
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else
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@ -649,8 +650,8 @@ vorbis_read_sample (SF_PRIVATE *psf, void *ptr, sf_count_t lens, convert_func *t
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return i ;
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if (nn == 2)
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{ /* Ran over a hole. loc is now out of date, need to recalculate. */
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vdata->loc = odata->pkt [odata->pkt_len - 1].granulepos ;
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vdata->loc -= vorbis_calculate_page_duration (psf) ;
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vdata->loc = odata->pkt [odata->pkt_len - 1].granulepos -
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vorbis_calculate_page_duration (psf) ;
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}
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} ;
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@ -791,11 +792,130 @@ vorbis_write_d (SF_PRIVATE *psf, const double *ptr, sf_count_t lens)
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return lens ;
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} /* vorbis_write_d */
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static int
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vorbis_skip (SF_PRIVATE *psf, uint64_t target)
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{ OGG_PRIVATE *odata = (OGG_PRIVATE *) psf->container_data ;
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VORBIS_PRIVATE *vdata = (VORBIS_PRIVATE *) psf->codec_data ;
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ogg_packet *pkt ;
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int thisblock, lastblock, nn ;
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const int blocksize = vorbis_info_blocksize (&vdata->vinfo, 1) ;
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/* Read out any samples in the decoder if any. */
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thisblock = vorbis_synthesis_pcmout (&vdata->vdsp, NULL) ;
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if (thisblock > 0)
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{ if ((uint64_t) thisblock + vdata->loc >= target)
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thisblock = SF_MIN (thisblock, (int) (target - vdata->loc)) ;
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vorbis_synthesis_read (&vdata->vdsp, thisblock) ;
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vdata->loc += thisblock ;
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if (vdata->loc == target)
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return 0 ;
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} ;
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lastblock = 0 ;
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for ( ; vdata->loc < target ; )
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{ /* Ensure there are unpacked packets. */
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if (odata->pkt_indx == odata->pkt_len)
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{ /* Page out of packets, load and unpack the next page. */
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nn = ogg_stream_unpack_page (psf, odata) ;
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if (nn < 0)
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return nn ;
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if (nn == 0)
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break ;
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if (nn == 2)
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{ /* Ran over a hole. loc is now out of date, need to recalculate. */
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vdata->loc = odata->pkt [odata->pkt_len - 1].granulepos -
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vorbis_calculate_page_duration (psf) ;
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}
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if (target < vdata->loc)
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{ /* Our target is inside the hole :-( */
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return 0 ;
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} ;
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} ;
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pkt = &odata->pkt [odata->pkt_indx] ;
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thisblock = vorbis_packet_blocksize (&vdata->vinfo, pkt) ;
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if (thisblock < 0)
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{ /* Not an audio packet */
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odata->pkt_indx++ ;
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continue ;
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} ;
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if (lastblock)
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{ vdata->loc += ((lastblock + thisblock) / 4) ;
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} ;
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/* Check to see if the block contains our target */
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if (vdata->loc + ((thisblock + blocksize) / 4) >= target)
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break ;
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/* Block is before the target. Track for state, but don't decode. */
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odata->pkt_indx++ ;
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vorbis_synthesis_trackonly (&vdata->vblock, pkt) ;
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vorbis_synthesis_blockin (&vdata->vdsp, &vdata->vblock) ;
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lastblock = thisblock ;
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} ;
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/* We are at the correct block, but still need to consume samples to reach
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** our target. */
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vorbis_read_sample (psf, (void *) NULL, (target - vdata->loc) * psf->sf.channels, vorbis_rnull) ;
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return 0 ;
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} /* vorbis_skip */
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static int
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vorbis_seek_trysearch (SF_PRIVATE *psf, uint64_t target_gp)
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{ OGG_PRIVATE *odata = (OGG_PRIVATE *) psf->container_data ;
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VORBIS_PRIVATE *vdata = (VORBIS_PRIVATE *) psf->codec_data ;
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uint64_t best_gp, search_target_gp ;
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int ret ;
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/* Can't bisect a file we don't know the end of (cannot seek). */
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if (vdata->pcm_end == (uint64_t) -1)
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return 0 ;
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/* If the target is for the near future, don't bother bisecting, just skip
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** to it. */
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if (target_gp >= vdata->loc &&
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target_gp - vdata->loc < ((unsigned) (VORBIS_SEEK_THRESHOLD) * psf->sf.samplerate))
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return 0 ;
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/* Search for a position a half large-block before our target. As Vorbis is
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** lapped, every sample position come from two blocks, the "left" half of
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** one block and the "right" half of the previous block. The granule
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** position of an Ogg page of a Vorbis stream is the sample offset of the
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** last finished sample in the stream that can be decoded from a page. A
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** page also contains another half-block of samples waiting to be lapped
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** with the first half-block of samples from the next page.
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**
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** Searching for a sample one half of a large block before our target
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** guarantees we always load a page containing the previous half block
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** required to decode the target. Downside is we can't use best_gp
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** parameter of the page seek function. */
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search_target_gp = vorbis_info_blocksize (&vdata->vinfo, 1) / 2 ;
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search_target_gp = search_target_gp < target_gp ? target_gp - search_target_gp : 0 ;
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ret = ogg_stream_seek_page_search (psf, odata, search_target_gp, vdata->pcm_start,
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vdata->pcm_end, &best_gp, psf->dataoffset, vdata->last_page) ;
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if (ret >= 0)
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{ ret = ogg_stream_unpack_page (psf, odata) ;
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if (ret == 1)
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{ /* Recalculate our granule position */
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vdata->loc = odata->pkt [odata->pkt_len - 1].granulepos -
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vorbis_calculate_page_duration (psf) ;
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vorbis_synthesis_restart (&vdata->vdsp) ;
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} ;
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} ;
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return ret ;
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} /* vorbis_seek_trysearch */
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static sf_count_t
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vorbis_seek (SF_PRIVATE *psf, int UNUSED (mode), sf_count_t offset)
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{ OGG_PRIVATE *odata = (OGG_PRIVATE *) psf->container_data ;
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VORBIS_PRIVATE *vdata = (VORBIS_PRIVATE *) psf->codec_data ;
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sf_count_t target ;
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uint64_t target_gp ;
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int ret ;
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if (odata == NULL || vdata == NULL)
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@ -807,63 +927,29 @@ vorbis_seek (SF_PRIVATE *psf, int UNUSED (mode), sf_count_t offset)
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} ;
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if (psf->file.mode == SFM_READ)
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{ target = offset + vdata->pcm_start ;
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{ target_gp = (uint64_t) offset + vdata->pcm_start ;
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ret = vorbis_seek_trysearch (psf, target_gp) ;
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/*
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** If the end of the file is know, and the seek isn't for the near
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** future, do a search of the file for a good place to start.
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*/
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ret = 0 ;
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if ((vdata->pcm_end != (uint64_t) -1) &&
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(target < vdata->loc || target - vdata->loc > (2 * psf->sf.samplerate)))
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{ uint64_t best_gp ;
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best_gp = vdata->pcm_start ;
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ret = ogg_stream_seek_page_search (psf, odata, target, vdata->pcm_start,
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vdata->pcm_end, &best_gp, psf->dataoffset, vdata->last_page) ;
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if (ret >= 0)
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{ ret = ogg_stream_unpack_page (psf, odata) ;
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if (ret == 1)
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{ vdata->loc = best_gp ;
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vorbis_synthesis_restart (&vdata->vdsp) ;
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} ;
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} ;
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} ;
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if (ret >= 0 && offset + (sf_count_t) vdata->pcm_start >= vdata->loc)
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target = offset + vdata->pcm_start - vdata->loc ;
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else
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if (ret < 0 || vdata->loc > target_gp)
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{ /* Search failed (bad data?), reset to the beginning of the stream. */
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psf_log_printf (psf, "Seek search failed. Reading through stream from start.\n") ;
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ogg_stream_reset_serialno (&odata->ostream, odata->ostream.serialno) ;
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odata->pkt_len = 0 ;
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odata->pkt_indx = 0 ;
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ogg_sync_fseek (psf, psf->dataoffset, SEEK_SET) ;
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vdata->loc = 0 ;
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vorbis_synthesis_restart (&vdata->vdsp) ;
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target = offset ;
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} ;
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while (target > 0)
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{ sf_count_t m = target > 4096 ? 4096 : target ;
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/*
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** Need to multiply by channels here because the seek is done in
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** terms of frames and the read function is done in terms of
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** samples.
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*/
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vorbis_read_sample (psf, (void *) NULL, m * psf->sf.channels, vorbis_rnull) ;
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target -= m ;
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} ;
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vorbis_skip (psf, target_gp) ;
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return vdata->loc - vdata->pcm_start ;
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} ;
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return 0 ;
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psf->error = SFE_BAD_SEEK ;
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return ((sf_count_t) -1) ;
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} /* vorbis_seek */
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static int
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vorbis_byterate (SF_PRIVATE *psf)
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{
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@ -877,9 +963,13 @@ static sf_count_t
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vorbis_calculate_page_duration (SF_PRIVATE *psf)
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{ OGG_PRIVATE *odata = (OGG_PRIVATE *) psf->container_data ;
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VORBIS_PRIVATE *vdata = (VORBIS_PRIVATE *) psf->codec_data ;
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long thisblock, lastblock ;
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int thisblock, lastblock, i ;
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sf_count_t duration ;
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int i ;
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/*
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** Calculate how many samples can be decoded from blocks in this page,
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** accounting for the fact that blocks are 1/2 lapped.
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*/
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lastblock = -1 ;
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duration = 0 ;
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@ -893,7 +983,7 @@ vorbis_calculate_page_duration (SF_PRIVATE *psf)
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} ;
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return duration ;
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}
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} /* vorbis_calculate_page_duration */
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#else /* HAVE_EXTERNAL_XIPH_LIBS */
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