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libavformat/adtsenc.c

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00001 /*
00002  * ADTS muxer.
00003  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
00004  *                    Mans Rullgard <mans@mansr.com>
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include "libavcodec/get_bits.h"
00024 #include "libavcodec/put_bits.h"
00025 #include "libavcodec/avcodec.h"
00026 #include "libavcodec/mpeg4audio.h"
00027 #include "avformat.h"
00028 #include "adts.h"
00029 
00030 int ff_adts_decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
00031 {
00032     GetBitContext gb;
00033     PutBitContext pb;
00034     MPEG4AudioConfig m4ac;
00035     int off;
00036 
00037     init_get_bits(&gb, buf, size * 8);
00038     off = ff_mpeg4audio_get_config(&m4ac, buf, size);
00039     if (off < 0)
00040         return off;
00041     skip_bits_long(&gb, off);
00042     adts->objecttype        = m4ac.object_type - 1;
00043     adts->sample_rate_index = m4ac.sampling_index;
00044     adts->channel_conf      = m4ac.chan_config;
00045 
00046     if (adts->objecttype > 3U) {
00047         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
00048         return -1;
00049     }
00050     if (adts->sample_rate_index == 15) {
00051         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
00052         return -1;
00053     }
00054     if (get_bits(&gb, 1)) {
00055         av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
00056         return -1;
00057     }
00058     if (get_bits(&gb, 1)) {
00059         av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
00060         return -1;
00061     }
00062     if (get_bits(&gb, 1)) {
00063         av_log(s, AV_LOG_ERROR, "Extension flag is not allowed in ADTS\n");
00064         return -1;
00065     }
00066     if (!adts->channel_conf) {
00067         init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
00068 
00069         put_bits(&pb, 3, 5); //ID_PCE
00070         adts->pce_size = (ff_copy_pce_data(&pb, &gb) + 3) / 8;
00071         flush_put_bits(&pb);
00072     }
00073 
00074     adts->write_adts = 1;
00075 
00076     return 0;
00077 }
00078 
00079 static int adts_write_header(AVFormatContext *s)
00080 {
00081     ADTSContext *adts = s->priv_data;
00082     AVCodecContext *avc = s->streams[0]->codec;
00083 
00084     if (avc->extradata_size > 0 &&
00085             ff_adts_decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
00086         return -1;
00087 
00088     return 0;
00089 }
00090 
00091 int ff_adts_write_frame_header(ADTSContext *ctx,
00092                                uint8_t *buf, int size, int pce_size)
00093 {
00094     PutBitContext pb;
00095 
00096     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
00097 
00098     /* adts_fixed_header */
00099     put_bits(&pb, 12, 0xfff);   /* syncword */
00100     put_bits(&pb, 1, 0);        /* ID */
00101     put_bits(&pb, 2, 0);        /* layer */
00102     put_bits(&pb, 1, 1);        /* protection_absent */
00103     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
00104     put_bits(&pb, 4, ctx->sample_rate_index);
00105     put_bits(&pb, 1, 0);        /* private_bit */
00106     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
00107     put_bits(&pb, 1, 0);        /* original_copy */
00108     put_bits(&pb, 1, 0);        /* home */
00109 
00110     /* adts_variable_header */
00111     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
00112     put_bits(&pb, 1, 0);        /* copyright_identification_start */
00113     put_bits(&pb, 13, ADTS_HEADER_SIZE + size + pce_size); /* aac_frame_length */
00114     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
00115     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
00116 
00117     flush_put_bits(&pb);
00118 
00119     return 0;
00120 }
00121 
00122 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
00123 {
00124     ADTSContext *adts = s->priv_data;
00125     AVIOContext *pb = s->pb;
00126     uint8_t buf[ADTS_HEADER_SIZE];
00127 
00128     if (!pkt->size)
00129         return 0;
00130     if (adts->write_adts) {
00131         ff_adts_write_frame_header(adts, buf, pkt->size, adts->pce_size);
00132         avio_write(pb, buf, ADTS_HEADER_SIZE);
00133         if (adts->pce_size) {
00134             avio_write(pb, adts->pce_data, adts->pce_size);
00135             adts->pce_size = 0;
00136         }
00137     }
00138     avio_write(pb, pkt->data, pkt->size);
00139     avio_flush(pb);
00140 
00141     return 0;
00142 }
00143 
00144 AVOutputFormat ff_adts_muxer = {
00145     "adts",
00146     NULL_IF_CONFIG_SMALL("ADTS AAC"),
00147     "audio/aac",
00148     "aac,adts",
00149     sizeof(ADTSContext),
00150     CODEC_ID_AAC,
00151     CODEC_ID_NONE,
00152     adts_write_header,
00153     adts_write_packet,
00154 };

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