/* * RAW AC-3 and E-AC-3 demuxer * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com> * * 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 "config_components.h" #include "libavutil/avassert.h"#include "libavutil/crc.h"#include "libavcodec/ac3_parser.h"#include "avformat.h"#include "demux.h"#include "rawdec.h" static int ac3_eac3_probe(const AVProbeData *p, enum AVCodecID expected_codec_id){    int max_frames, first_frames = 0, frames;    const uint8_t *buf, *buf2, *end;    enum AVCodecID codec_id = AV_CODEC_ID_AC3;     max_frames = 0;    buf = p->buf;    end = buf + p->buf_size;     for(; buf < end; buf++) {        if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)                        && !(buf[0] == 0x77 && buf[1] == 0x0B) )            continue;        buf2 = buf;         for(frames = 0; buf2 < end; frames++) {            uint8_t buf3[4096];            uint8_t bitstream_id;            uint16_t frame_size;            int i, ret;             if(!memcmp(buf2, "\x1\x10", 2)) {                if (buf2 + 16 > end)                    break;                buf2+=16;            }            if (buf[0] == 0x77 && buf[1] == 0x0B) {                for(i=0; i<8; i+=2) {                    buf3[i  ] = buf2[i+1];                    buf3[i+1] = buf2[i  ];                }                ret = av_ac3_parse_header(buf3, 8, &bitstream_id,                                          &frame_size);            }else                ret = av_ac3_parse_header(buf2, end - buf2, &bitstream_id,                                          &frame_size);            if (ret < 0)                break;            if(buf2 + frame_size > end)                break;            if (buf[0] == 0x77 && buf[1] == 0x0B) {                av_assert0(frame_size <= sizeof(buf3));                for(i = 8; i < frame_size; i += 2) {                    buf3[i  ] = buf2[i+1];                    buf3[i+1] = buf2[i  ];                }                if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf3 + 2, frame_size - 2))                    break;            } else {                if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, frame_size - 2))                    break;            }            if (bitstream_id > 10)                codec_id = AV_CODEC_ID_EAC3;            buf2 += frame_size;        }        max_frames = FFMAX(max_frames, frames);        if(buf == p->buf)            first_frames = frames;    }    if(codec_id != expected_codec_id) return 0;    // keep this in sync with mp3 probe, both need to avoid    // issues with MPEG-files!    if   (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;    else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;    else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2;    else if(max_frames>=1) return 1;    else                   return 0;} #if CONFIG_AC3_DEMUXERstatic int ac3_probe(const AVProbeData *p){    return ac3_eac3_probe(p, AV_CODEC_ID_AC3);} const FFInputFormat ff_ac3_demuxer = {    .p.name         = "ac3",    .p.long_name    = NULL_IF_CONFIG_SMALL("raw AC-3"),    .p.flags        = AVFMT_GENERIC_INDEX,    .p.extensions   = "ac3",    .p.priv_class   = &ff_raw_demuxer_class,    .read_probe     = ac3_probe,    .read_header    = ff_raw_audio_read_header,    .read_packet    = ff_raw_read_partial_packet,    .raw_codec_id   = AV_CODEC_ID_AC3,    .priv_data_size = sizeof(FFRawDemuxerContext),};#endif #if CONFIG_EAC3_DEMUXERstatic int eac3_probe(const AVProbeData *p){    return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);} const FFInputFormat ff_eac3_demuxer = {    .p.name         = "eac3",    .p.long_name    = NULL_IF_CONFIG_SMALL("raw E-AC-3"),    .p.flags        = AVFMT_GENERIC_INDEX,    .p.extensions   = "eac3,ec3",    .p.priv_class   = &ff_raw_demuxer_class,    .read_probe     = eac3_probe,    .read_header    = ff_raw_audio_read_header,    .read_packet    = ff_raw_read_partial_packet,    .raw_codec_id   = AV_CODEC_ID_EAC3,    .priv_data_size = sizeof(FFRawDemuxerContext),};#endif