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- /*
- * 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 "mpegaudiodecheader.h"
- #include "libavutil/common.h"
- #include "libavformat/apetag.h" // for APE tag.
- #include "libavformat/id3v1.h" // for ID3v1_TAG_SIZE
- typedef struct MpegAudioParseContext {
- ParseContext pc;
- int frame_size;
- uint32_t header;
- int header_count;
- int no_bitrate;
- } MpegAudioParseContext;
- #define MPA_HEADER_SIZE 4
- /* header + layer + freq + lsf/mpeg25 */
- #define SAME_HEADER_MASK \
- (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
- 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;
- ParseContext *pc = &s->pc;
- uint32_t state= pc->state;
- int i;
- int next= END_NOT_FOUND;
- int flush = !buf_size;
- for(i=0; i<buf_size; ){
- if(s->frame_size){
- int inc= FFMIN(buf_size - i, s->frame_size);
- i += inc;
- s->frame_size -= inc;
- state = 0;
- if(!s->frame_size){
- next= i;
- break;
- }
- }else{
- while(i<buf_size){
- int ret, sr, channels, bit_rate, frame_size;
- enum AVCodecID codec_id = avctx->codec_id;
- state= (state<<8) + buf[i++];
- ret = ff_mpa_decode_header(state, &sr, &channels, &frame_size, &bit_rate, &codec_id);
- if (ret < 4) {
- if (i > 4)
- s->header_count = -2;
- } else {
- int header_threshold = avctx->codec_id != AV_CODEC_ID_NONE && avctx->codec_id != codec_id;
- if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
- s->header_count= -3;
- s->header= state;
- s->header_count++;
- s->frame_size = ret-4;
- if (s->header_count > header_threshold) {
- avctx->sample_rate= sr;
- avctx->channels = channels;
- s1->duration = frame_size;
- avctx->codec_id = codec_id;
- if (s->no_bitrate || !avctx->bit_rate) {
- s->no_bitrate = 1;
- avctx->bit_rate += (bit_rate - avctx->bit_rate) / (s->header_count - header_threshold);
- }
- }
- if (s1->flags & PARSER_FLAG_COMPLETE_FRAMES) {
- s->frame_size = 0;
- next = buf_size;
- } else if (codec_id == AV_CODEC_ID_MP3ADU) {
- avpriv_report_missing_feature(avctx,
- "MP3ADU full parser");
- *poutbuf = NULL;
- *poutbuf_size = 0;
- return buf_size; /* parsers must not return error codes */
- }
- break;
- }
- }
- }
- }
- pc->state= state;
- if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
- *poutbuf = NULL;
- *poutbuf_size = 0;
- return buf_size;
- }
- if (flush && buf_size >= ID3v1_TAG_SIZE && memcmp(buf, "TAG", 3) == 0) {
- *poutbuf = NULL;
- *poutbuf_size = 0;
- return next;
- }
- if (flush && buf_size >= APE_TAG_FOOTER_BYTES && memcmp(buf, APE_TAG_PREAMBLE, 8) == 0) {
- *poutbuf = NULL;
- *poutbuf_size = 0;
- return next;
- }
- *poutbuf = buf;
- *poutbuf_size = buf_size;
- return next;
- }
- AVCodecParser ff_mpegaudio_parser = {
- .codec_ids = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3, AV_CODEC_ID_MP3ADU },
- .priv_data_size = sizeof(MpegAudioParseContext),
- .parser_parse = mpegaudio_parse,
- .parser_close = ff_parse_close,
- };
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