yading@11: /*
yading@11:  * LATM/LOAS muxer
yading@11:  * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
yading@11:  *
yading@11:  * This file is part of Libav.
yading@11:  *
yading@11:  * Libav is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * Libav is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with Libav; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavcodec/get_bits.h"
yading@11: #include "libavcodec/put_bits.h"
yading@11: #include "libavcodec/avcodec.h"
yading@11: #include "libavcodec/mpeg4audio.h"
yading@11: #include "libavutil/opt.h"
yading@11: #include "avformat.h"
yading@11: #include "rawenc.h"
yading@11: 
yading@11: #define MAX_EXTRADATA_SIZE 1024
yading@11: 
yading@11: typedef struct {
yading@11:     AVClass *av_class;
yading@11:     int off;
yading@11:     int channel_conf;
yading@11:     int object_type;
yading@11:     int counter;
yading@11:     int mod;
yading@11:     uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024];
yading@11: } LATMContext;
yading@11: 
yading@11: static const AVOption options[] = {
yading@11:     {"smc-interval", "StreamMuxConfig interval.",
yading@11:      offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.i64 = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
yading@11:     {NULL},
yading@11: };
yading@11: 
yading@11: static const AVClass latm_muxer_class = {
yading@11:     .class_name = "LATM/LOAS muxer",
yading@11:     .item_name  = av_default_item_name,
yading@11:     .option     = options,
yading@11:     .version    = LIBAVUTIL_VERSION_INT,
yading@11: };
yading@11: 
yading@11: static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
yading@11: {
yading@11:     MPEG4AudioConfig m4ac;
yading@11: 
yading@11:     if (size > MAX_EXTRADATA_SIZE) {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Extradata is larger than currently supported.\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11:     ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
yading@11:     if (ctx->off < 0)
yading@11:         return ctx->off;
yading@11: 
yading@11:     if (ctx->object_type == AOT_ALS && (ctx->off & 7)) {
yading@11:         // as long as avpriv_mpeg4audio_get_config works correctly this is impossible
yading@11:         av_log(ctx, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11:     /* FIXME: are any formats not allowed in LATM? */
yading@11: 
yading@11:     if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11:     ctx->channel_conf = m4ac.chan_config;
yading@11:     ctx->object_type  = m4ac.object_type;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int latm_write_header(AVFormatContext *s)
yading@11: {
yading@11:     LATMContext *ctx = s->priv_data;
yading@11:     AVCodecContext *avctx = s->streams[0]->codec;
yading@11: 
yading@11:     if (avctx->codec_id == AV_CODEC_ID_AAC_LATM)
yading@11:         return 0;
yading@11: 
yading@11:     if (avctx->extradata_size > 0 &&
yading@11:         latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
yading@11:         return AVERROR_INVALIDDATA;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
yading@11: {
yading@11:     LATMContext *ctx = s->priv_data;
yading@11:     AVCodecContext *avctx = s->streams[0]->codec;
yading@11:     int header_size;
yading@11: 
yading@11:     /* AudioMuxElement */
yading@11:     put_bits(bs, 1, !!ctx->counter);
yading@11: 
yading@11:     if (!ctx->counter) {
yading@11:         /* StreamMuxConfig */
yading@11:         put_bits(bs, 1, 0); /* audioMuxVersion */
yading@11:         put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
yading@11:         put_bits(bs, 6, 0); /* numSubFrames */
yading@11:         put_bits(bs, 4, 0); /* numProgram */
yading@11:         put_bits(bs, 3, 0); /* numLayer */
yading@11: 
yading@11:         /* AudioSpecificConfig */
yading@11:         if (ctx->object_type == AOT_ALS) {
yading@11:             header_size = avctx->extradata_size-(ctx->off >> 3);
yading@11:             avpriv_copy_bits(bs, &avctx->extradata[ctx->off >> 3], header_size);
yading@11:         } else {
yading@11:             // + 3 assumes not scalable and dependsOnCoreCoder == 0,
yading@11:             // see decode_ga_specific_config in libavcodec/aacdec.c
yading@11:             avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3);
yading@11: 
yading@11:             if (!ctx->channel_conf) {
yading@11:                 GetBitContext gb;
yading@11:                 init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
yading@11:                 skip_bits_long(&gb, ctx->off + 3);
yading@11:                 avpriv_copy_pce_data(bs, &gb);
yading@11:             }
yading@11:         }
yading@11: 
yading@11:         put_bits(bs, 3, 0); /* frameLengthType */
yading@11:         put_bits(bs, 8, 0xff); /* latmBufferFullness */
yading@11: 
yading@11:         put_bits(bs, 1, 0); /* otherDataPresent */
yading@11:         put_bits(bs, 1, 0); /* crcCheckPresent */
yading@11:     }
yading@11: 
yading@11:     ctx->counter++;
yading@11:     ctx->counter %= ctx->mod;
yading@11: }
yading@11: 
yading@11: static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     LATMContext *ctx = s->priv_data;
yading@11:     AVIOContext *pb = s->pb;
yading@11:     PutBitContext bs;
yading@11:     int i, len;
yading@11:     uint8_t loas_header[] = "\x56\xe0\x00";
yading@11: 
yading@11:     if (s->streams[0]->codec->codec_id == AV_CODEC_ID_AAC_LATM)
yading@11:         return ff_raw_write_packet(s, pkt);
yading@11: 
yading@11:     if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
yading@11:         av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11: 
yading@11:     if (!s->streams[0]->codec->extradata) {
yading@11:         if(pkt->size > 2 && pkt->data[0] == 0x56 && (pkt->data[1] >> 4) == 0xe &&
yading@11:             (AV_RB16(pkt->data + 1) & 0x1FFF) + 3 == pkt->size)
yading@11:             return ff_raw_write_packet(s, pkt);
yading@11:         else
yading@11:             return AVERROR_INVALIDDATA;
yading@11:     }
yading@11: 
yading@11:     if (pkt->size > 0x1fff)
yading@11:         goto too_large;
yading@11: 
yading@11:     init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE);
yading@11: 
yading@11:     latm_write_frame_header(s, &bs);
yading@11: 
yading@11:     /* PayloadLengthInfo() */
yading@11:     for (i = 0; i <= pkt->size-255; i+=255)
yading@11:         put_bits(&bs, 8, 255);
yading@11: 
yading@11:     put_bits(&bs, 8, pkt->size-i);
yading@11: 
yading@11:     /* The LATM payload is written unaligned */
yading@11: 
yading@11:     /* PayloadMux() */
yading@11:     if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) {
yading@11:         // Convert byte-aligned DSE to non-aligned.
yading@11:         // Due to the input format encoding we know that
yading@11:         // it is naturally byte-aligned in the input stream,
yading@11:         // so there are no padding bits to account for.
yading@11:         // To avoid having to add padding bits and rearrange
yading@11:         // the whole stream we just remove the byte-align flag.
yading@11:         // This allows us to remux our FATE AAC samples into latm
yading@11:         // files that are still playable with minimal effort.
yading@11:         put_bits(&bs, 8, pkt->data[0] & 0xfe);
yading@11:         avpriv_copy_bits(&bs, pkt->data + 1, 8*pkt->size - 8);
yading@11:     } else
yading@11:         avpriv_copy_bits(&bs, pkt->data, 8*pkt->size);
yading@11: 
yading@11:     avpriv_align_put_bits(&bs);
yading@11:     flush_put_bits(&bs);
yading@11: 
yading@11:     len = put_bits_count(&bs) >> 3;
yading@11: 
yading@11:     if (len > 0x1fff)
yading@11:         goto too_large;
yading@11: 
yading@11:     loas_header[1] |= (len >> 8) & 0x1f;
yading@11:     loas_header[2] |= len & 0xff;
yading@11: 
yading@11:     avio_write(pb, loas_header, 3);
yading@11:     avio_write(pb, ctx->buffer, len);
yading@11: 
yading@11:     return 0;
yading@11: 
yading@11: too_large:
yading@11:     av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n");
yading@11:     return AVERROR_INVALIDDATA;
yading@11: }
yading@11: 
yading@11: AVOutputFormat ff_latm_muxer = {
yading@11:     .name           = "latm",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
yading@11:     .mime_type      = "audio/MP4A-LATM",
yading@11:     .extensions     = "latm,loas",
yading@11:     .priv_data_size = sizeof(LATMContext),
yading@11:     .audio_codec    = AV_CODEC_ID_AAC,
yading@11:     .video_codec    = AV_CODEC_ID_NONE,
yading@11:     .write_header   = latm_write_header,
yading@11:     .write_packet   = latm_write_packet,
yading@11:     .priv_class     = &latm_muxer_class,
yading@11: };