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libavformat/latmenc.c

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00001 /*
00002  * LATM/LOAS muxer
00003  * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * Libav is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavcodec/get_bits.h"
00023 #include "libavcodec/put_bits.h"
00024 #include "libavcodec/avcodec.h"
00025 #include "libavcodec/mpeg4audio.h"
00026 #include "libavutil/opt.h"
00027 #include "avformat.h"
00028 
00029 typedef struct {
00030     AVClass *av_class;
00031     int off;
00032     int channel_conf;
00033     int object_type;
00034     int counter;
00035     int mod;
00036 } LATMContext;
00037 
00038 static const AVOption options[] = {
00039     {"smc-interval", "StreamMuxConfig interval.",
00040      offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.dbl = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
00041     {NULL},
00042 };
00043 
00044 static const AVClass latm_muxer_class = {
00045     .class_name = "LATM/LOAS muxer",
00046     .item_name  = av_default_item_name,
00047     .option     = options,
00048     .version    = LIBAVUTIL_VERSION_INT,
00049 };
00050 
00051 static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
00052 {
00053     GetBitContext gb;
00054     MPEG4AudioConfig m4ac;
00055 
00056     init_get_bits(&gb, buf, size * 8);
00057     ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
00058     if (ctx->off < 0)
00059         return ctx->off;
00060     skip_bits_long(&gb, ctx->off);
00061 
00062     /* FIXME: are any formats not allowed in LATM? */
00063 
00064     if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
00065         av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
00066         return AVERROR_INVALIDDATA;
00067     }
00068     ctx->channel_conf = m4ac.chan_config;
00069     ctx->object_type  = m4ac.object_type;
00070 
00071     return 0;
00072 }
00073 
00074 static int latm_write_header(AVFormatContext *s)
00075 {
00076     LATMContext *ctx = s->priv_data;
00077     AVCodecContext *avctx = s->streams[0]->codec;
00078 
00079     if (avctx->extradata_size > 0 &&
00080         latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
00081         return AVERROR_INVALIDDATA;
00082 
00083     return 0;
00084 }
00085 
00086 static int latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
00087 {
00088     LATMContext *ctx = s->priv_data;
00089     AVCodecContext *avctx = s->streams[0]->codec;
00090     GetBitContext gb;
00091     int header_size;
00092 
00093     /* AudioMuxElement */
00094     put_bits(bs, 1, !!ctx->counter);
00095 
00096     if (!ctx->counter) {
00097         init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
00098 
00099         /* StreamMuxConfig */
00100         put_bits(bs, 1, 0); /* audioMuxVersion */
00101         put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
00102         put_bits(bs, 6, 0); /* numSubFrames */
00103         put_bits(bs, 4, 0); /* numProgram */
00104         put_bits(bs, 3, 0); /* numLayer */
00105 
00106         /* AudioSpecificConfig */
00107         if (ctx->object_type == AOT_ALS) {
00108             header_size = avctx->extradata_size-(ctx->off + 7) >> 3;
00109             avpriv_copy_bits(bs, &avctx->extradata[ctx->off], header_size);
00110         } else {
00111             avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3);
00112 
00113             if (!ctx->channel_conf) {
00114                 avpriv_copy_pce_data(bs, &gb);
00115             }
00116         }
00117 
00118         put_bits(bs, 3, 0); /* frameLengthType */
00119         put_bits(bs, 8, 0xff); /* latmBufferFullness */
00120 
00121         put_bits(bs, 1, 0); /* otherDataPresent */
00122         put_bits(bs, 1, 0); /* crcCheckPresent */
00123     }
00124 
00125     ctx->counter++;
00126     ctx->counter %= ctx->mod;
00127 
00128     return 0;
00129 }
00130 
00131 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
00132 {
00133     AVIOContext *pb = s->pb;
00134     PutBitContext bs;
00135     int i, len;
00136     uint8_t loas_header[] = "\x56\xe0\x00";
00137     uint8_t *buf;
00138 
00139     if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
00140         av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
00141         return AVERROR_INVALIDDATA;
00142     }
00143 
00144     buf = av_malloc(pkt->size+1024);
00145     if (!buf)
00146         return AVERROR(ENOMEM);
00147 
00148     init_put_bits(&bs, buf, pkt->size+1024);
00149 
00150     latm_write_frame_header(s, &bs);
00151 
00152     /* PayloadLengthInfo() */
00153     for (i = 0; i <= pkt->size-255; i+=255)
00154         put_bits(&bs, 8, 255);
00155 
00156     put_bits(&bs, 8, pkt->size-i);
00157 
00158     /* The LATM payload is written unaligned */
00159 
00160     /* PayloadMux() */
00161     for (i = 0; i < pkt->size; i++)
00162         put_bits(&bs, 8, pkt->data[i]);
00163 
00164     avpriv_align_put_bits(&bs);
00165     flush_put_bits(&bs);
00166 
00167     len = put_bits_count(&bs) >> 3;
00168 
00169     loas_header[1] |= (len >> 8) & 0x1f;
00170     loas_header[2] |= len & 0xff;
00171 
00172     avio_write(pb, loas_header, 3);
00173     avio_write(pb, buf, len);
00174 
00175     av_free(buf);
00176 
00177     return 0;
00178 }
00179 
00180 AVOutputFormat ff_latm_muxer = {
00181     .name           = "latm",
00182     .long_name      = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
00183     .mime_type      = "audio/MP4A-LATM",
00184     .extensions     = "latm",
00185     .priv_data_size = sizeof(LATMContext),
00186     .audio_codec    = CODEC_ID_AAC,
00187     .video_codec    = CODEC_ID_NONE,
00188     .write_header   = latm_write_header,
00189     .write_packet   = latm_write_packet,
00190     .priv_class     = &latm_muxer_class,
00191 };
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