vgmstream/src/coding/mpeg_decoder.c
halleyscometsw 97ebe328c8 support for mpeg audio in genh
git-svn-id: https://vgmstream.svn.sourceforge.net/svnroot/vgmstream@292 51a99a44-fe44-0410-b1ba-c3e57ba2b86b
2008-07-06 15:33:38 +00:00

130 lines
4.2 KiB
C

#include "../vgmstream.h"
#ifdef VGM_USE_MPEG
#include <string.h>
#include <mpg123.h>
#include "coding.h"
#include "../util.h"
/* mono, mpg123 expects frames of 0x414 (160kbps, 22050Hz) but they
* actually vary and are much shorter */
void decode_fake_mpeg2_l2(VGMSTREAMCHANNEL *stream,
mpeg_codec_data * data,
sample * outbuf, int32_t samples_to_do) {
int samples_done = 0;
while (samples_done < samples_to_do) {
size_t bytes_done;
int rc;
if (!data->buffer_full) {
/* fill buffer up to next frame ending (or file ending) */
int bytes_into_header = 0;
const uint8_t header[4] = {0xff,0xf5,0xe0,0xc0};
off_t frame_offset = 0;
/* assume that we are starting at a header, skip it and look for the
* next one */
read_streamfile(data->buffer, stream->offset+frame_offset, 4,
stream->streamfile);
frame_offset += 4;
do {
uint8_t byte;
byte =
read_8bit(stream->offset+frame_offset,stream->streamfile);
data->buffer[frame_offset] = byte;
frame_offset++;
if (byte == header[bytes_into_header]) {
bytes_into_header++;
} else {
/* This might have been the first byte of the header, so
* we need to check again.
* No need to get more complicated than this, though, since
* there are no repeated characters in the search string. */
if (bytes_into_header>0) {
frame_offset--;
}
bytes_into_header=0;
}
if (bytes_into_header==4) {
break;
}
} while (frame_offset < AHX_EXPECTED_FRAME_SIZE);
if (bytes_into_header==4) frame_offset-=4;
memset(data->buffer+frame_offset,0,
AHX_EXPECTED_FRAME_SIZE-frame_offset);
data->buffer_full = 1;
data->buffer_used = 0;
stream->offset += frame_offset;
}
if (!data->buffer_used) {
rc = mpg123_decode(data->m,
data->buffer,AHX_EXPECTED_FRAME_SIZE,
(unsigned char *)(outbuf+samples_done),
(samples_to_do-samples_done)*sizeof(sample),
&bytes_done);
data->buffer_used = 1;
} else {
rc = mpg123_decode(data->m,
NULL,0,
(unsigned char *)(outbuf+samples_done),
(samples_to_do-samples_done)*sizeof(sample),
&bytes_done);
}
if (rc == MPG123_NEED_MORE) data->buffer_full = 0;
samples_done += bytes_done/sizeof(sample);
}
}
/* decode anything mpg123 can */
void decode_mpeg(VGMSTREAMCHANNEL *stream,
mpeg_codec_data * data,
sample * outbuf, int32_t samples_to_do, int channels) {
int samples_done = 0;
while (samples_done < samples_to_do) {
size_t bytes_done;
int rc;
if (!data->buffer_full) {
data->bytes_in_buffer = read_streamfile(data->buffer,
stream->offset,MPEG_BUFFER_SIZE,stream->streamfile);
data->buffer_full = 1;
data->buffer_used = 0;
stream->offset += data->bytes_in_buffer;
}
if (!data->buffer_used) {
rc = mpg123_decode(data->m,
data->buffer,data->bytes_in_buffer,
(unsigned char *)(outbuf+samples_done*channels),
(samples_to_do-samples_done)*sizeof(sample)*channels,
&bytes_done);
data->buffer_used = 1;
} else {
rc = mpg123_decode(data->m,
NULL,0,
(unsigned char *)(outbuf+samples_done*channels),
(samples_to_do-samples_done)*sizeof(sample)*channels,
&bytes_done);
}
if (rc == MPG123_NEED_MORE) data->buffer_full = 0;
samples_done += bytes_done/sizeof(sample)/channels;
}
}
#endif