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 #include "rawenc.h"
00029 
00030 typedef struct {
00031     AVClass *av_class;
00032     int off;
00033     int channel_conf;
00034     int object_type;
00035     int counter;
00036     int mod;
00037 } LATMContext;
00038 
00039 static const AVOption options[] = {
00040     {"smc-interval", "StreamMuxConfig interval.",
00041      offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.dbl = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
00042     {NULL},
00043 };
00044 
00045 static const AVClass latm_muxer_class = {
00046     .class_name = "LATM/LOAS muxer",
00047     .item_name  = av_default_item_name,
00048     .option     = options,
00049     .version    = LIBAVUTIL_VERSION_INT,
00050 };
00051 
00052 static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
00053 {
00054     GetBitContext gb;
00055     MPEG4AudioConfig m4ac;
00056 
00057     init_get_bits(&gb, buf, size * 8);
00058     ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
00059     if (ctx->off < 0)
00060         return ctx->off;
00061     skip_bits_long(&gb, ctx->off);
00062 
00063     /* FIXME: are any formats not allowed in LATM? */
00064 
00065     if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
00066         av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
00067         return AVERROR_INVALIDDATA;
00068     }
00069     ctx->channel_conf = m4ac.chan_config;
00070     ctx->object_type  = m4ac.object_type;
00071 
00072     return 0;
00073 }
00074 
00075 static int latm_write_header(AVFormatContext *s)
00076 {
00077     LATMContext *ctx = s->priv_data;
00078     AVCodecContext *avctx = s->streams[0]->codec;
00079 
00080     if (avctx->codec_id == CODEC_ID_AAC_LATM)
00081         return 0;
00082 
00083     if (avctx->extradata_size > 0 &&
00084         latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
00085         return AVERROR_INVALIDDATA;
00086 
00087     return 0;
00088 }
00089 
00090 static int latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
00091 {
00092     LATMContext *ctx = s->priv_data;
00093     AVCodecContext *avctx = s->streams[0]->codec;
00094     GetBitContext gb;
00095     int header_size;
00096 
00097     /* AudioMuxElement */
00098     put_bits(bs, 1, !!ctx->counter);
00099 
00100     if (!ctx->counter) {
00101         init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
00102 
00103         /* StreamMuxConfig */
00104         put_bits(bs, 1, 0); /* audioMuxVersion */
00105         put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
00106         put_bits(bs, 6, 0); /* numSubFrames */
00107         put_bits(bs, 4, 0); /* numProgram */
00108         put_bits(bs, 3, 0); /* numLayer */
00109 
00110         /* AudioSpecificConfig */
00111         if (ctx->object_type == AOT_ALS) {
00112             header_size = avctx->extradata_size-(ctx->off + 7) >> 3;
00113             avpriv_copy_bits(bs, &avctx->extradata[ctx->off], header_size);
00114         } else {
00115             avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3);
00116 
00117             if (!ctx->channel_conf) {
00118                 avpriv_copy_pce_data(bs, &gb);
00119             }
00120         }
00121 
00122         put_bits(bs, 3, 0); /* frameLengthType */
00123         put_bits(bs, 8, 0xff); /* latmBufferFullness */
00124 
00125         put_bits(bs, 1, 0); /* otherDataPresent */
00126         put_bits(bs, 1, 0); /* crcCheckPresent */
00127     }
00128 
00129     ctx->counter++;
00130     ctx->counter %= ctx->mod;
00131 
00132     return 0;
00133 }
00134 
00135 static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
00136 {
00137     AVIOContext *pb = s->pb;
00138     PutBitContext bs;
00139     int i, len;
00140     uint8_t loas_header[] = "\x56\xe0\x00";
00141     uint8_t *buf;
00142 
00143     if (s->streams[0]->codec->codec_id == CODEC_ID_AAC_LATM)
00144         return ff_raw_write_packet(s, pkt);
00145 
00146     if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
00147         av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
00148         return AVERROR_INVALIDDATA;
00149     }
00150 
00151     buf = av_malloc(pkt->size+1024);
00152     if (!buf)
00153         return AVERROR(ENOMEM);
00154 
00155     init_put_bits(&bs, buf, pkt->size+1024);
00156 
00157     latm_write_frame_header(s, &bs);
00158 
00159     /* PayloadLengthInfo() */
00160     for (i = 0; i <= pkt->size-255; i+=255)
00161         put_bits(&bs, 8, 255);
00162 
00163     put_bits(&bs, 8, pkt->size-i);
00164 
00165     /* The LATM payload is written unaligned */
00166 
00167     /* PayloadMux() */
00168     for (i = 0; i < pkt->size; i++)
00169         put_bits(&bs, 8, pkt->data[i]);
00170 
00171     avpriv_align_put_bits(&bs);
00172     flush_put_bits(&bs);
00173 
00174     len = put_bits_count(&bs) >> 3;
00175 
00176     loas_header[1] |= (len >> 8) & 0x1f;
00177     loas_header[2] |= len & 0xff;
00178 
00179     avio_write(pb, loas_header, 3);
00180     avio_write(pb, buf, len);
00181 
00182     av_free(buf);
00183 
00184     return 0;
00185 }
00186 
00187 AVOutputFormat ff_latm_muxer = {
00188     .name           = "latm",
00189     .long_name      = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
00190     .mime_type      = "audio/MP4A-LATM",
00191     .extensions     = "latm,loas",
00192     .priv_data_size = sizeof(LATMContext),
00193     .audio_codec    = CODEC_ID_AAC,
00194     .video_codec    = CODEC_ID_NONE,
00195     .write_header   = latm_write_header,
00196     .write_packet   = latm_write_packet,
00197     .priv_class     = &latm_muxer_class,
00198 };