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rockbox/apps/codecs/libm4a/m4a.c

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C
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2005 Dave Chapman, 2011 Andree Buschmann
*
* 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 <codecs.h>
#include <inttypes.h>
#include "m4a.h"
/* Implementation of the stream.h functions used by libalac */
#define _Swap32(v) do { \
v = (((v) & 0x000000FF) << 0x18) | \
(((v) & 0x0000FF00) << 0x08) | \
(((v) & 0x00FF0000) >> 0x08) | \
(((v) & 0xFF000000) >> 0x18); } while(0)
#define _Swap16(v) do { \
v = (((v) & 0x00FF) << 0x08) | \
(((v) & 0xFF00) >> 0x08); } while (0)
/* A normal read without any byte-swapping */
void stream_read(stream_t *stream, size_t size, void *buf)
{
stream->ci->read_filebuf(buf,size);
if (stream->ci->curpos >= stream->ci->filesize) { stream->eof=1; }
}
int32_t stream_read_int32(stream_t *stream)
{
int32_t v;
stream_read(stream, 4, &v);
#ifdef ROCKBOX_LITTLE_ENDIAN
_Swap32(v);
#endif
return v;
}
int32_t stream_tell(stream_t *stream)
{
return stream->ci->curpos;
}
uint32_t stream_read_uint32(stream_t *stream)
{
uint32_t v;
stream_read(stream, 4, &v);
#ifdef ROCKBOX_LITTLE_ENDIAN
_Swap32(v);
#endif
return v;
}
int16_t stream_read_int16(stream_t *stream)
{
int16_t v;
stream_read(stream, 2, &v);
#ifdef ROCKBOX_LITTLE_ENDIAN
_Swap16(v);
#endif
return v;
}
uint16_t stream_read_uint16(stream_t *stream)
{
uint16_t v;
stream_read(stream, 2, &v);
#ifdef ROCKBOX_LITTLE_ENDIAN
_Swap16(v);
#endif
return v;
}
int8_t stream_read_int8(stream_t *stream)
{
int8_t v;
stream_read(stream, 1, &v);
return v;
}
uint8_t stream_read_uint8(stream_t *stream)
{
uint8_t v;
stream_read(stream, 1, &v);
return v;
}
void stream_skip(stream_t *stream, size_t skip)
{
stream->ci->advance_buffer(skip);
}
void stream_seek(stream_t *stream, size_t offset)
{
stream->ci->seek_buffer(offset);
}
int stream_eof(stream_t *stream)
{
return stream->eof;
}
void stream_create(stream_t *stream,struct codec_api* ci)
{
stream->ci=ci;
stream->eof=0;
}
/* Check if there is a dedicated byte position contained for the given frame.
* Return this byte position in case of success or return -1. This allows to
* skip empty samples.
* During standard playback the search result (index i) will always increase.
* Therefor we save this index and let the caller set this value again as start
* index when calling m4a_check_sample_offset() for the next frame. This
* reduces the overall loop count significantly. */
int m4a_check_sample_offset(demux_res_t *demux_res, uint32_t frame, uint32_t *start)
{
uint32_t i = *start;
for (i=0; i<demux_res->num_lookup_table; ++i)
{
if (demux_res->lookup_table[i].sample > frame ||
demux_res->lookup_table[i].offset == 0)
return -1;
if (demux_res->lookup_table[i].sample == frame)
break;
}
*start = i;
return demux_res->lookup_table[i].offset;
}
/* Find the exact or preceding frame in lookup_table[]. Return both frame
* and byte position of this match. */
static void gather_offset(demux_res_t *demux_res, uint32_t *frame, uint32_t *offset)
{
uint32_t i = 0;
for (i=0; i<demux_res->num_lookup_table; ++i)
{
if (demux_res->lookup_table[i].offset == 0)
break;
if (demux_res->lookup_table[i].sample > *frame)
break;
}
i = (i>0) ? i-1 : 0; /* We want the last chunk _before_ *frame. */
*frame = demux_res->lookup_table[i].sample;
*offset = demux_res->lookup_table[i].offset;
}
/* Seek to desired sound sample location. Return 1 on success (and modify
* sound_samples_done and current_sample), 0 if failed.
*
* Find the sample (=frame) that contains the given sound sample, find a best
* fit for this sample in the lookup_table[], seek to the byte position. */
unsigned int m4a_seek(demux_res_t* demux_res, stream_t* stream,
uint32_t sound_sample_loc, uint32_t* sound_samples_done,
int* current_sample)
{
uint32_t i = 0;
uint32_t tmp_var, tmp_cnt, tmp_dur;
uint32_t new_sample = 0; /* Holds the amount of chunks/frames. */
uint32_t new_sound_sample = 0; /* Sums up total amount of samples. */
uint32_t new_pos; /* Holds the desired chunk/frame index. */
/* First check we have the appropriate metadata - we should always
* have it.
*/
if (!demux_res->num_time_to_samples || !demux_res->num_sample_byte_sizes)
{
return 0;
}
/* Find the destination block from time_to_sample array */
time_to_sample_t *tab = demux_res->time_to_sample;
while (i < demux_res->num_time_to_samples)
{
tmp_cnt = tab[i].sample_count;
tmp_dur = tab[i].sample_duration;
tmp_var = tmp_cnt * tmp_dur;
if (sound_sample_loc <= new_sound_sample + tmp_var)
{
tmp_var = (sound_sample_loc - new_sound_sample);
new_sample += tmp_var / tmp_dur;
new_sound_sample += tmp_var;
break;
}
new_sample += tmp_cnt;
new_sound_sample += tmp_var;
++i;
}
/* We know the new sample (=frame), now calculate the file position. */
gather_offset(demux_res, &new_sample, &new_pos);
/* We know the new file position, so let's try to seek to it */
if (stream->ci->seek_buffer(new_pos))
{
*sound_samples_done = new_sound_sample;
*current_sample = new_sample;
return 1;
}
return 0;
}
/* Seek to the sample containing file_loc. Return 1 on success (and modify
* sound_samples_done and current_sample), 0 if failed.
*
* Seeking uses the following arrays:
*
* 1) the lookup_table array contains the file offset for the first sample
* of each chunk.
*
* 2) the time_to_sample array contains the duration (in sound samples)
* of each sample of data.
*
* Locate the chunk containing location (using lookup_table), find the first
* sample of that chunk (using lookup_table). Then use time_to_sample to
* calculate the sound_samples_done value.
*/
unsigned int m4a_seek_raw(demux_res_t* demux_res, stream_t* stream,
uint32_t file_loc, uint32_t* sound_samples_done,
int* current_sample)
{
uint32_t i;
uint32_t chunk_sample = 0;
uint32_t total_samples = 0;
uint32_t new_sound_sample = 0;
uint32_t tmp_dur;
uint32_t tmp_cnt;
uint32_t new_pos;
/* We know the desired byte offset, search for the chunk right before.
* Return the associated sample to this chunk as chunk_sample. */
for (i=0; i < demux_res->num_lookup_table; ++i)
{
if (demux_res->lookup_table[i].offset > file_loc)
break;
}
i = (i>0) ? i-1 : 0; /* We want the last chunk _before_ file_loc. */
chunk_sample = demux_res->lookup_table[i].sample;
new_pos = demux_res->lookup_table[i].offset;
/* Get sound sample offset. */
i = 0;
time_to_sample_t *tab2 = demux_res->time_to_sample;
while (i < demux_res->num_time_to_samples)
{
tmp_dur = tab2[i].sample_duration;
tmp_cnt = tab2[i].sample_count;
total_samples += tmp_cnt;
new_sound_sample += tmp_cnt * tmp_dur;
if (chunk_sample <= total_samples)
{
new_sound_sample += (chunk_sample - total_samples) * tmp_dur;
break;
}
++i;
}
/* Go to the new file position. */
if (stream->ci->seek_buffer(new_pos))
{
*sound_samples_done = new_sound_sample;
*current_sample = chunk_sample;
return 1;
}
return 0;
}
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