mirror of https://github.com/FFmpeg/FFmpeg.git
Originally committed as revision 8899 to svn://svn.ffmpeg.org/ffmpeg/trunkpull/126/head
Aurelien Jacobs
18 years ago
parent
d2e911fac8
commit
0cb4172803
3 changed files with 221 additions and 198 deletions
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/*
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* MPEG Audio parser |
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* Copyright (c) 2003 Fabrice Bellard. |
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* Copyright (c) 2003 Michael Niedermayer. |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "parser.h" |
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#include "mpegaudio.h" |
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typedef struct MpegAudioParseContext { |
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uint8_t inbuf[MPA_MAX_CODED_FRAME_SIZE]; /* input buffer */ |
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uint8_t *inbuf_ptr; |
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int frame_size; |
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int free_format_frame_size; |
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int free_format_next_header; |
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uint32_t header; |
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int header_count; |
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} MpegAudioParseContext; |
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#define MPA_HEADER_SIZE 4 |
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/* header + layer + bitrate + freq + lsf/mpeg25 */ |
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#undef SAME_HEADER_MASK /* mpegaudio.h defines different version */ |
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#define SAME_HEADER_MASK \ |
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(0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19)) |
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static int mpegaudio_parse_init(AVCodecParserContext *s1) |
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{ |
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MpegAudioParseContext *s = s1->priv_data; |
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s->inbuf_ptr = s->inbuf; |
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return 0; |
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} |
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static int mpegaudio_parse(AVCodecParserContext *s1, |
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AVCodecContext *avctx, |
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uint8_t **poutbuf, int *poutbuf_size, |
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const uint8_t *buf, int buf_size) |
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{ |
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MpegAudioParseContext *s = s1->priv_data; |
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int len, ret, sr; |
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uint32_t header; |
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const uint8_t *buf_ptr; |
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*poutbuf = NULL; |
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*poutbuf_size = 0; |
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buf_ptr = buf; |
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while (buf_size > 0) { |
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len = s->inbuf_ptr - s->inbuf; |
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if (s->frame_size == 0) { |
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/* special case for next header for first frame in free
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format case (XXX: find a simpler method) */ |
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if (s->free_format_next_header != 0) { |
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s->inbuf[0] = s->free_format_next_header >> 24; |
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s->inbuf[1] = s->free_format_next_header >> 16; |
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s->inbuf[2] = s->free_format_next_header >> 8; |
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s->inbuf[3] = s->free_format_next_header; |
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s->inbuf_ptr = s->inbuf + 4; |
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s->free_format_next_header = 0; |
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goto got_header; |
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} |
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/* no header seen : find one. We need at least MPA_HEADER_SIZE
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bytes to parse it */ |
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len = FFMIN(MPA_HEADER_SIZE - len, buf_size); |
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if (len > 0) { |
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memcpy(s->inbuf_ptr, buf_ptr, len); |
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buf_ptr += len; |
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buf_size -= len; |
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s->inbuf_ptr += len; |
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} |
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if ((s->inbuf_ptr - s->inbuf) >= MPA_HEADER_SIZE) { |
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got_header: |
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header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | |
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(s->inbuf[2] << 8) | s->inbuf[3]; |
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ret = mpa_decode_header(avctx, header, &sr); |
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if (ret < 0) { |
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s->header_count= -2; |
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/* no sync found : move by one byte (inefficient, but simple!) */ |
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memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); |
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s->inbuf_ptr--; |
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dprintf(avctx, "skip %x\n", header); |
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/* reset free format frame size to give a chance
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to get a new bitrate */ |
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s->free_format_frame_size = 0; |
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} else { |
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if((header&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header) |
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s->header_count= -3; |
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s->header= header; |
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s->header_count++; |
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s->frame_size = ret; |
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#if 0 |
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/* free format: prepare to compute frame size */ |
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if (decode_header(s, header) == 1) { |
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s->frame_size = -1; |
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} |
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#endif |
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} |
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if(s->header_count > 1) |
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avctx->sample_rate= sr; |
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} |
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} else |
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#if 0 |
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if (s->frame_size == -1) { |
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/* free format : find next sync to compute frame size */ |
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len = MPA_MAX_CODED_FRAME_SIZE - len; |
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if (len > buf_size) |
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len = buf_size; |
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if (len == 0) { |
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/* frame too long: resync */ |
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s->frame_size = 0; |
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memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); |
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s->inbuf_ptr--; |
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} else { |
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uint8_t *p, *pend; |
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uint32_t header1; |
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int padding; |
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memcpy(s->inbuf_ptr, buf_ptr, len); |
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/* check for header */ |
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p = s->inbuf_ptr - 3; |
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pend = s->inbuf_ptr + len - 4; |
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while (p <= pend) { |
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header = (p[0] << 24) | (p[1] << 16) | |
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(p[2] << 8) | p[3]; |
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header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | |
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(s->inbuf[2] << 8) | s->inbuf[3]; |
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/* check with high probability that we have a
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valid header */ |
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if ((header & SAME_HEADER_MASK) == |
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(header1 & SAME_HEADER_MASK)) { |
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/* header found: update pointers */ |
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len = (p + 4) - s->inbuf_ptr; |
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buf_ptr += len; |
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buf_size -= len; |
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s->inbuf_ptr = p; |
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/* compute frame size */ |
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s->free_format_next_header = header; |
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s->free_format_frame_size = s->inbuf_ptr - s->inbuf; |
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padding = (header1 >> 9) & 1; |
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if (s->layer == 1) |
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s->free_format_frame_size -= padding * 4; |
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else |
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s->free_format_frame_size -= padding; |
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dprintf(avctx, "free frame size=%d padding=%d\n", |
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s->free_format_frame_size, padding); |
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decode_header(s, header1); |
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goto next_data; |
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} |
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p++; |
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} |
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/* not found: simply increase pointers */ |
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buf_ptr += len; |
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s->inbuf_ptr += len; |
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buf_size -= len; |
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} |
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} else |
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#endif |
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if (len < s->frame_size) { |
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if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE) |
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s->frame_size = MPA_MAX_CODED_FRAME_SIZE; |
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len = FFMIN(s->frame_size - len, buf_size); |
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memcpy(s->inbuf_ptr, buf_ptr, len); |
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buf_ptr += len; |
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s->inbuf_ptr += len; |
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buf_size -= len; |
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} |
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if(s->frame_size > 0 && buf_ptr - buf == s->inbuf_ptr - s->inbuf |
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&& buf_size + buf_ptr - buf >= s->frame_size){ |
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if(s->header_count > 0){ |
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*poutbuf = buf; |
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*poutbuf_size = s->frame_size; |
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} |
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buf_ptr = buf + s->frame_size; |
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s->inbuf_ptr = s->inbuf; |
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s->frame_size = 0; |
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break; |
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} |
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// next_data:
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if (s->frame_size > 0 && |
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(s->inbuf_ptr - s->inbuf) >= s->frame_size) { |
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if(s->header_count > 0){ |
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*poutbuf = s->inbuf; |
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*poutbuf_size = s->inbuf_ptr - s->inbuf; |
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} |
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s->inbuf_ptr = s->inbuf; |
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s->frame_size = 0; |
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break; |
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} |
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} |
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return buf_ptr - buf; |
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} |
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AVCodecParser mpegaudio_parser = { |
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{ CODEC_ID_MP2, CODEC_ID_MP3 }, |
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sizeof(MpegAudioParseContext), |
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mpegaudio_parse_init, |
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mpegaudio_parse, |
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NULL, |
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}; |
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