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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 #define ADTS_MAX_FRAME_BYTES ((1 << 13) - 1)
00031 
00032 int ff_adts_decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
00033 {
00034     GetBitContext gb;
00035     PutBitContext pb;
00036     MPEG4AudioConfig m4ac;
00037     int off;
00038 
00039     init_get_bits(&gb, buf, size * 8);
00040     off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
00041     if (off < 0)
00042         return off;
00043     skip_bits_long(&gb, off);
00044     adts->objecttype        = m4ac.object_type - 1;
00045     adts->sample_rate_index = m4ac.sampling_index;
00046     adts->channel_conf      = m4ac.chan_config;
00047 
00048     if (adts->objecttype > 3U) {
00049         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
00050         return -1;
00051     }
00052     if (adts->sample_rate_index == 15) {
00053         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
00054         return -1;
00055     }
00056     if (get_bits(&gb, 1)) {
00057         av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
00058         return -1;
00059     }
00060     if (get_bits(&gb, 1)) {
00061         av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
00062         return -1;
00063     }
00064     if (get_bits(&gb, 1)) {
00065         av_log(s, AV_LOG_ERROR, "Extension flag is not allowed in ADTS\n");
00066         return -1;
00067     }
00068     if (!adts->channel_conf) {
00069         init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
00070 
00071         put_bits(&pb, 3, 5); //ID_PCE
00072         adts->pce_size = (avpriv_copy_pce_data(&pb, &gb) + 3) / 8;
00073         flush_put_bits(&pb);
00074     }
00075 
00076     adts->write_adts = 1;
00077 
00078     return 0;
00079 }
00080 
00081 static int adts_write_header(AVFormatContext *s)
00082 {
00083     ADTSContext *adts = s->priv_data;
00084     AVCodecContext *avc = s->streams[0]->codec;
00085 
00086     if (avc->extradata_size > 0 &&
00087             ff_adts_decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
00088         return -1;
00089 
00090     return 0;
00091 }
00092 
00093 int ff_adts_write_frame_header(ADTSContext *ctx,
00094                                uint8_t *buf, int size, int pce_size)
00095 {
00096     PutBitContext pb;
00097 
00098     unsigned full_frame_size = (unsigned)ADTS_HEADER_SIZE + size + pce_size;
00099     if (full_frame_size > ADTS_MAX_FRAME_BYTES) {
00100         av_log(NULL, AV_LOG_ERROR, "ADTS frame size too large: %u (max %d)\n",
00101                full_frame_size, ADTS_MAX_FRAME_BYTES);
00102         return AVERROR_INVALIDDATA;
00103     }
00104 
00105     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
00106 
00107     /* adts_fixed_header */
00108     put_bits(&pb, 12, 0xfff);   /* syncword */
00109     put_bits(&pb, 1, 0);        /* ID */
00110     put_bits(&pb, 2, 0);        /* layer */
00111     put_bits(&pb, 1, 1);        /* protection_absent */
00112     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
00113     put_bits(&pb, 4, ctx->sample_rate_index);
00114     put_bits(&pb, 1, 0);        /* private_bit */
00115     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
00116     put_bits(&pb, 1, 0);        /* original_copy */
00117     put_bits(&pb, 1, 0);        /* home */
00118 
00119     /* adts_variable_header */
00120     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
00121     put_bits(&pb, 1, 0);        /* copyright_identification_start */
00122     put_bits(&pb, 13, full_frame_size); /* aac_frame_length */
00123     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
00124     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
00125 
00126     flush_put_bits(&pb);
00127 
00128     return 0;
00129 }
00130 
00131 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
00132 {
00133     ADTSContext *adts = s->priv_data;
00134     AVIOContext *pb = s->pb;
00135     uint8_t buf[ADTS_HEADER_SIZE];
00136 
00137     if (!pkt->size)
00138         return 0;
00139     if (adts->write_adts) {
00140         int err = ff_adts_write_frame_header(adts, buf, pkt->size,
00141                                              adts->pce_size);
00142         if (err < 0)
00143             return err;
00144         avio_write(pb, buf, ADTS_HEADER_SIZE);
00145         if (adts->pce_size) {
00146             avio_write(pb, adts->pce_data, adts->pce_size);
00147             adts->pce_size = 0;
00148         }
00149     }
00150     avio_write(pb, pkt->data, pkt->size);
00151     avio_flush(pb);
00152 
00153     return 0;
00154 }
00155 
00156 AVOutputFormat ff_adts_muxer = {
00157     .name              = "adts",
00158     .long_name         = NULL_IF_CONFIG_SMALL("ADTS AAC"),
00159     .mime_type         = "audio/aac",
00160     .extensions        = "aac,adts",
00161     .priv_data_size    = sizeof(ADTSContext),
00162     .audio_codec       = CODEC_ID_AAC,
00163     .video_codec       = CODEC_ID_NONE,
00164     .write_header      = adts_write_header,
00165     .write_packet      = adts_write_packet,
00166 };
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