/* * LATM/LOAS muxer * Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "libavcodec/get_bits.h" #include "libavcodec/put_bits.h" #include "libavcodec/avcodec.h" #include "libavcodec/mpeg4audio.h" #include "libavutil/opt.h" #include "avformat.h" #include "rawenc.h" #define MAX_EXTRADATA_SIZE 1024 typedef struct { AVClass *av_class; int off; int channel_conf; int object_type; int counter; int mod; uint8_t buffer[0x1fff + MAX_EXTRADATA_SIZE + 1024]; } LATMContext; static const AVOption options[] = { {"smc-interval", "StreamMuxConfig interval.", offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.i64 = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM}, {NULL}, }; static const AVClass latm_muxer_class = { .class_name = "LATM/LOAS muxer", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, }; static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size) { MPEG4AudioConfig m4ac; if (size > MAX_EXTRADATA_SIZE) { av_log(ctx, AV_LOG_ERROR, "Extradata is larger than currently supported.\n"); return AVERROR_INVALIDDATA; } ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1); if (ctx->off < 0) return ctx->off; if (ctx->object_type == AOT_ALS && (ctx->off & 7)) { // as long as avpriv_mpeg4audio_get_config works correctly this is impossible av_log(ctx, AV_LOG_ERROR, "BUG: ALS offset is not byte-aligned\n"); return AVERROR_INVALIDDATA; } /* FIXME: are any formats not allowed in LATM? */ if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) { av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type); return AVERROR_INVALIDDATA; } ctx->channel_conf = m4ac.chan_config; ctx->object_type = m4ac.object_type; return 0; } static int latm_write_header(AVFormatContext *s) { LATMContext *ctx = s->priv_data; AVCodecContext *avctx = s->streams[0]->codec; if (avctx->codec_id == AV_CODEC_ID_AAC_LATM) return 0; if (avctx->extradata_size > 0 && latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0) return AVERROR_INVALIDDATA; return 0; } static void latm_write_frame_header(AVFormatContext *s, PutBitContext *bs) { LATMContext *ctx = s->priv_data; AVCodecContext *avctx = s->streams[0]->codec; int header_size; /* AudioMuxElement */ put_bits(bs, 1, !!ctx->counter); if (!ctx->counter) { /* StreamMuxConfig */ put_bits(bs, 1, 0); /* audioMuxVersion */ put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */ put_bits(bs, 6, 0); /* numSubFrames */ put_bits(bs, 4, 0); /* numProgram */ put_bits(bs, 3, 0); /* numLayer */ /* AudioSpecificConfig */ if (ctx->object_type == AOT_ALS) { header_size = avctx->extradata_size-(ctx->off >> 3); avpriv_copy_bits(bs, &avctx->extradata[ctx->off >> 3], header_size); } else { // + 3 assumes not scalable and dependsOnCoreCoder == 0, // see decode_ga_specific_config in libavcodec/aacdec.c avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3); if (!ctx->channel_conf) { GetBitContext gb; init_get_bits8(&gb, avctx->extradata, avctx->extradata_size); skip_bits_long(&gb, ctx->off + 3); avpriv_copy_pce_data(bs, &gb); } } put_bits(bs, 3, 0); /* frameLengthType */ put_bits(bs, 8, 0xff); /* latmBufferFullness */ put_bits(bs, 1, 0); /* otherDataPresent */ put_bits(bs, 1, 0); /* crcCheckPresent */ } ctx->counter++; ctx->counter %= ctx->mod; } static int latm_write_packet(AVFormatContext *s, AVPacket *pkt) { LATMContext *ctx = s->priv_data; AVIOContext *pb = s->pb; PutBitContext bs; int i, len; uint8_t loas_header[] = "\x56\xe0\x00"; if (s->streams[0]->codec->codec_id == AV_CODEC_ID_AAC_LATM) return ff_raw_write_packet(s, pkt); if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) { av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n"); return AVERROR_INVALIDDATA; } if (!s->streams[0]->codec->extradata) { if(pkt->size > 2 && pkt->data[0] == 0x56 && (pkt->data[1] >> 4) == 0xe && (AV_RB16(pkt->data + 1) & 0x1FFF) + 3 == pkt->size) return ff_raw_write_packet(s, pkt); else return AVERROR_INVALIDDATA; } if (pkt->size > 0x1fff) goto too_large; init_put_bits(&bs, ctx->buffer, pkt->size+1024+MAX_EXTRADATA_SIZE); latm_write_frame_header(s, &bs); /* PayloadLengthInfo() */ for (i = 0; i <= pkt->size-255; i+=255) put_bits(&bs, 8, 255); put_bits(&bs, 8, pkt->size-i); /* The LATM payload is written unaligned */ /* PayloadMux() */ if (pkt->size && (pkt->data[0] & 0xe1) == 0x81) { // Convert byte-aligned DSE to non-aligned. // Due to the input format encoding we know that // it is naturally byte-aligned in the input stream, // so there are no padding bits to account for. // To avoid having to add padding bits and rearrange // the whole stream we just remove the byte-align flag. // This allows us to remux our FATE AAC samples into latm // files that are still playable with minimal effort. put_bits(&bs, 8, pkt->data[0] & 0xfe); avpriv_copy_bits(&bs, pkt->data + 1, 8*pkt->size - 8); } else avpriv_copy_bits(&bs, pkt->data, 8*pkt->size); avpriv_align_put_bits(&bs); flush_put_bits(&bs); len = put_bits_count(&bs) >> 3; if (len > 0x1fff) goto too_large; loas_header[1] |= (len >> 8) & 0x1f; loas_header[2] |= len & 0xff; avio_write(pb, loas_header, 3); avio_write(pb, ctx->buffer, len); return 0; too_large: av_log(s, AV_LOG_ERROR, "LATM packet size larger than maximum size 0x1fff\n"); return AVERROR_INVALIDDATA; } AVOutputFormat ff_latm_muxer = { .name = "latm", .long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"), .mime_type = "audio/MP4A-LATM", .extensions = "latm,loas", .priv_data_size = sizeof(LATMContext), .audio_codec = AV_CODEC_ID_AAC, .video_codec = AV_CODEC_ID_NONE, .write_header = latm_write_header, .write_packet = latm_write_packet, .priv_class = &latm_muxer_class, .flags = AVFMT_NOTIMESTAMPS, };