forked from len0rd/rockbox
4dd3c2b33e
Seeking doesn't work well in M4A files with very few chunks due to the seek method used (chunk based using the info in the 'stco' atom). According to libm4a/demux.c the expected seek resolution using this method is 1/4 to 1/2 seconds. However, ffmpeg generates files with a 1 megabyte chunk size, so the resolution is much worse than expected on some files: around 30-40 seconds at 256kbps. There was a bug with the seek position reported back to Rockbox: the codec pretended it could seek exactly to the requested sample, but it would only seek to the start of a chunk. This could leave the UI in a confusing state because the real playback position was different from what the elapsed time showed. Fix this by recalculating the reported sample position using the chunk start. To fix the low seek accuracy, use the table in the 'stsz' atom to skip individual packets within a chunk. This is very accurate, but it takes a lot of RAM to allocate the table. Currently the table is not allowed to use more than half of the codec RAM, which should suffice for short files on most targets. On files where the table is too large the codec will fall back to the less accurate chunk-based seek method. Change-Id: Ide38ea846c1cdd69691e9b1e1cd87eb0fa11cf78
139 lines
3.8 KiB
C
139 lines
3.8 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2005 Dave Chapman
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef _M4A_H
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#define _M4A_H
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#include <codecs.h>
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#include <inttypes.h>
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/* AAC codecdata appears to always be less than 8 bytes - see
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AudioSpecificConfig2 in libfaad/mp4.c
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ALAC codecdata appears to always be 44 bytes (see alac_set_info in
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libalac/alac.c) but my test file contains 56 bytes.
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So we go safe and round up to 64 bytes - if we find more than this,
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we give an error (even though we could possibly continue), so we
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can increase this buffer.
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*/
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#define MAX_CODECDATA_SIZE 64
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typedef struct {
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struct codec_api* ci;
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int eof;
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} stream_t;
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typedef uint32_t fourcc_t;
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typedef struct
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{
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uint32_t first_chunk;
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uint32_t num_samples;
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} sample_to_chunk_t;
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typedef struct
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{
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uint32_t sample_count;
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uint32_t sample_duration;
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} time_to_sample_t;
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typedef struct
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{
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uint32_t sample;
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uint32_t offset;
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} sample_offset_t;
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typedef struct
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{
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uint16_t num_channels;
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uint16_t sound_sample_size;
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uint32_t sound_sample_rate;
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fourcc_t format;
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void *buf;
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sample_to_chunk_t *sample_to_chunk;
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uint32_t num_sample_to_chunks;
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sample_offset_t *lookup_table;
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uint32_t num_lookup_table;
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time_to_sample_t *time_to_sample;
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uint32_t num_time_to_samples;
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uint32_t *sample_byte_sizes;
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uint32_t num_sample_byte_sizes;
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uint32_t codecdata_len;
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uint8_t codecdata[MAX_CODECDATA_SIZE];
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int mdat_offset;
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uint32_t mdat_len;
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#if 0
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void *mdat;
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#endif
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} demux_res_t;
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int qtmovie_read(stream_t *stream, demux_res_t *demux_res);
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#ifndef MAKEFOURCC
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#define MAKEFOURCC(ch0, ch1, ch2, ch3) ( \
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( (int32_t)(char)(ch0) << 24 ) | \
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( (int32_t)(char)(ch1) << 16 ) | \
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( (int32_t)(char)(ch2) << 8 ) | \
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( (int32_t)(char)(ch3) ) )
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#endif
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#ifndef SLPITFOURCC
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/* splits it into ch0, ch1, ch2, ch3 - use for printf's */
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#define SPLITFOURCC(code) \
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(char)((int32_t)code >> 24), \
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(char)((int32_t)code >> 16), \
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(char)((int32_t)code >> 8), \
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(char)code
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#endif
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void stream_read(stream_t *stream, size_t len, void *buf);
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int32_t stream_tell(stream_t *stream);
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int32_t stream_read_int32(stream_t *stream);
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uint32_t stream_read_uint32(stream_t *stream);
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uint16_t stream_read_uint16(stream_t *stream);
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uint8_t stream_read_uint8(stream_t *stream);
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void stream_skip(stream_t *stream, size_t skip);
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void stream_seek(stream_t *stream, size_t offset);
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int stream_eof(stream_t *stream);
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void stream_create(stream_t *stream,struct codec_api* ci);
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unsigned int get_sample_offset(demux_res_t *demux_res, uint32_t sample);
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unsigned int m4a_seek (demux_res_t* demux_res, stream_t* stream,
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uint32_t sound_sample_loc, uint32_t* sound_samples_done,
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int* current_sample);
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unsigned int m4a_seek_raw (demux_res_t* demux_res, stream_t* stream,
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uint32_t file_loc, uint32_t* sound_samples_done, int* current_sample);
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int m4a_check_sample_offset(demux_res_t *demux_res, uint32_t frame, uint32_t *start);
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#endif /* STREAM_H */
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