diff options
author | Aurelien Jacobs <aurel@gnuage.org> | 2007-05-05 22:08:16 +0400 |
---|---|---|
committer | Aurelien Jacobs <aurel@gnuage.org> | 2007-05-05 22:08:16 +0400 |
commit | 0cb417280384a014f9a339157ba79d61f847d998 (patch) | |
tree | 1dc3c8292a6fd710b668429e722f48187beed2ec /libavcodec/mpegaudio_parser.c | |
parent | d2e911fac826e8900514a7630eb4c0c9cf0ade5e (diff) |
move mpegaudio_parser in it's own file
Originally committed as revision 8899 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/mpegaudio_parser.c')
-rw-r--r-- | libavcodec/mpegaudio_parser.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/libavcodec/mpegaudio_parser.c b/libavcodec/mpegaudio_parser.c new file mode 100644 index 0000000000..32f52efa5a --- /dev/null +++ b/libavcodec/mpegaudio_parser.c @@ -0,0 +1,220 @@ +/* + * 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" + + +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)) + +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, + 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) { + s->inbuf[0] = s->free_format_next_header >> 24; + s->inbuf[1] = s->free_format_next_header >> 16; + s->inbuf[2] = s->free_format_next_header >> 8; + s->inbuf[3] = 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 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | + (s->inbuf[2] << 8) | s->inbuf[3]; + + ret = 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 (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 = (p[0] << 24) | (p[1] << 16) | + (p[2] << 8) | p[3]; + header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | + (s->inbuf[2] << 8) | s->inbuf[3]; + /* 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); + 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, +}; |