mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-20 22:41:11 +00:00
253 lines
8.5 KiB
C
253 lines
8.5 KiB
C
/*
|
|
* MPEG Audio parser
|
|
* Copyright (c) 2003 Fabrice Bellard.
|
|
* Copyright (c) 2003 Michael Niedermayer.
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "parser.h"
|
|
#include "mpegaudio.h"
|
|
#include "mpegaudiodecheader.h"
|
|
|
|
|
|
typedef struct MpegAudioParseContext {
|
|
uint8_t inbuf[MPA_MAX_CODED_FRAME_SIZE]; /* input buffer */
|
|
uint8_t *inbuf_ptr;
|
|
int frame_size;
|
|
int free_format_frame_size;
|
|
int free_format_next_header;
|
|
uint32_t header;
|
|
int header_count;
|
|
} MpegAudioParseContext;
|
|
|
|
#define MPA_HEADER_SIZE 4
|
|
|
|
/* header + layer + bitrate + freq + lsf/mpeg25 */
|
|
#undef SAME_HEADER_MASK /* mpegaudio.h defines different version */
|
|
#define SAME_HEADER_MASK \
|
|
(0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
|
|
|
|
/* useful helper to get mpeg audio stream infos. Return -1 if error in
|
|
header, otherwise the coded frame size in bytes */
|
|
int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate)
|
|
{
|
|
MPADecodeContext s1, *s = &s1;
|
|
s1.avctx = avctx;
|
|
|
|
if (ff_mpa_check_header(head) != 0)
|
|
return -1;
|
|
|
|
if (ff_mpegaudio_decode_header(s, head) != 0) {
|
|
return -1;
|
|
}
|
|
|
|
switch(s->layer) {
|
|
case 1:
|
|
avctx->frame_size = 384;
|
|
break;
|
|
case 2:
|
|
avctx->frame_size = 1152;
|
|
break;
|
|
default:
|
|
case 3:
|
|
if (s->lsf)
|
|
avctx->frame_size = 576;
|
|
else
|
|
avctx->frame_size = 1152;
|
|
break;
|
|
}
|
|
|
|
*sample_rate = s->sample_rate;
|
|
avctx->channels = s->nb_channels;
|
|
avctx->bit_rate = s->bit_rate;
|
|
avctx->sub_id = s->layer;
|
|
return s->frame_size;
|
|
}
|
|
|
|
static int mpegaudio_parse_init(AVCodecParserContext *s1)
|
|
{
|
|
MpegAudioParseContext *s = s1->priv_data;
|
|
s->inbuf_ptr = s->inbuf;
|
|
return 0;
|
|
}
|
|
|
|
static int mpegaudio_parse(AVCodecParserContext *s1,
|
|
AVCodecContext *avctx,
|
|
const uint8_t **poutbuf, int *poutbuf_size,
|
|
const uint8_t *buf, int buf_size)
|
|
{
|
|
MpegAudioParseContext *s = s1->priv_data;
|
|
int len, ret, sr;
|
|
uint32_t header;
|
|
const uint8_t *buf_ptr;
|
|
|
|
*poutbuf = NULL;
|
|
*poutbuf_size = 0;
|
|
buf_ptr = buf;
|
|
while (buf_size > 0) {
|
|
len = s->inbuf_ptr - s->inbuf;
|
|
if (s->frame_size == 0) {
|
|
/* special case for next header for first frame in free
|
|
format case (XXX: find a simpler method) */
|
|
if (s->free_format_next_header != 0) {
|
|
AV_WB32(s->inbuf, s->free_format_next_header);
|
|
s->inbuf_ptr = s->inbuf + 4;
|
|
s->free_format_next_header = 0;
|
|
goto got_header;
|
|
}
|
|
/* no header seen : find one. We need at least MPA_HEADER_SIZE
|
|
bytes to parse it */
|
|
len = FFMIN(MPA_HEADER_SIZE - len, buf_size);
|
|
if (len > 0) {
|
|
memcpy(s->inbuf_ptr, buf_ptr, len);
|
|
buf_ptr += len;
|
|
buf_size -= len;
|
|
s->inbuf_ptr += len;
|
|
}
|
|
if ((s->inbuf_ptr - s->inbuf) >= MPA_HEADER_SIZE) {
|
|
got_header:
|
|
header = AV_RB32(s->inbuf);
|
|
|
|
ret = ff_mpa_decode_header(avctx, header, &sr);
|
|
if (ret < 0) {
|
|
s->header_count= -2;
|
|
/* no sync found : move by one byte (inefficient, but simple!) */
|
|
memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);
|
|
s->inbuf_ptr--;
|
|
dprintf(avctx, "skip %x\n", header);
|
|
/* reset free format frame size to give a chance
|
|
to get a new bitrate */
|
|
s->free_format_frame_size = 0;
|
|
} else {
|
|
if((header&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
|
|
s->header_count= -3;
|
|
s->header= header;
|
|
s->header_count++;
|
|
s->frame_size = ret;
|
|
|
|
#if 0
|
|
/* free format: prepare to compute frame size */
|
|
if (ff_mpegaudio_decode_header(s, header) == 1) {
|
|
s->frame_size = -1;
|
|
}
|
|
#endif
|
|
if(s->header_count > 1)
|
|
avctx->sample_rate= sr;
|
|
}
|
|
}
|
|
} else
|
|
#if 0
|
|
if (s->frame_size == -1) {
|
|
/* free format : find next sync to compute frame size */
|
|
len = MPA_MAX_CODED_FRAME_SIZE - len;
|
|
if (len > buf_size)
|
|
len = buf_size;
|
|
if (len == 0) {
|
|
/* frame too long: resync */
|
|
s->frame_size = 0;
|
|
memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1);
|
|
s->inbuf_ptr--;
|
|
} else {
|
|
uint8_t *p, *pend;
|
|
uint32_t header1;
|
|
int padding;
|
|
|
|
memcpy(s->inbuf_ptr, buf_ptr, len);
|
|
/* check for header */
|
|
p = s->inbuf_ptr - 3;
|
|
pend = s->inbuf_ptr + len - 4;
|
|
while (p <= pend) {
|
|
header = AV_RB32(p);
|
|
header1 = AV_RB32(s->inbuf);
|
|
/* check with high probability that we have a
|
|
valid header */
|
|
if ((header & SAME_HEADER_MASK) ==
|
|
(header1 & SAME_HEADER_MASK)) {
|
|
/* header found: update pointers */
|
|
len = (p + 4) - s->inbuf_ptr;
|
|
buf_ptr += len;
|
|
buf_size -= len;
|
|
s->inbuf_ptr = p;
|
|
/* compute frame size */
|
|
s->free_format_next_header = header;
|
|
s->free_format_frame_size = s->inbuf_ptr - s->inbuf;
|
|
padding = (header1 >> 9) & 1;
|
|
if (s->layer == 1)
|
|
s->free_format_frame_size -= padding * 4;
|
|
else
|
|
s->free_format_frame_size -= padding;
|
|
dprintf(avctx, "free frame size=%d padding=%d\n",
|
|
s->free_format_frame_size, padding);
|
|
ff_mpegaudio_decode_header(s, header1);
|
|
goto next_data;
|
|
}
|
|
p++;
|
|
}
|
|
/* not found: simply increase pointers */
|
|
buf_ptr += len;
|
|
s->inbuf_ptr += len;
|
|
buf_size -= len;
|
|
}
|
|
} else
|
|
#endif
|
|
if (len < s->frame_size) {
|
|
if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE)
|
|
s->frame_size = MPA_MAX_CODED_FRAME_SIZE;
|
|
len = FFMIN(s->frame_size - len, buf_size);
|
|
memcpy(s->inbuf_ptr, buf_ptr, len);
|
|
buf_ptr += len;
|
|
s->inbuf_ptr += len;
|
|
buf_size -= len;
|
|
}
|
|
|
|
if(s->frame_size > 0 && buf_ptr - buf == s->inbuf_ptr - s->inbuf
|
|
&& buf_size + buf_ptr - buf >= s->frame_size){
|
|
if(s->header_count > 0){
|
|
*poutbuf = buf;
|
|
*poutbuf_size = s->frame_size;
|
|
}
|
|
buf_ptr = buf + s->frame_size;
|
|
s->inbuf_ptr = s->inbuf;
|
|
s->frame_size = 0;
|
|
break;
|
|
}
|
|
|
|
// next_data:
|
|
if (s->frame_size > 0 &&
|
|
(s->inbuf_ptr - s->inbuf) >= s->frame_size) {
|
|
if(s->header_count > 0){
|
|
*poutbuf = s->inbuf;
|
|
*poutbuf_size = s->inbuf_ptr - s->inbuf;
|
|
}
|
|
s->inbuf_ptr = s->inbuf;
|
|
s->frame_size = 0;
|
|
break;
|
|
}
|
|
}
|
|
return buf_ptr - buf;
|
|
}
|
|
|
|
|
|
AVCodecParser mpegaudio_parser = {
|
|
{ CODEC_ID_MP2, CODEC_ID_MP3 },
|
|
sizeof(MpegAudioParseContext),
|
|
mpegaudio_parse_init,
|
|
mpegaudio_parse,
|
|
NULL,
|
|
};
|