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* Copyright (c) 2011 Kieran Kunhya <kieran@kunhya.com>
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* This file is part of Libav.
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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#include "libavcodec/get_bits.h"
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#include "libavcodec/put_bits.h"
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#include "libavcodec/avcodec.h"
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#include "libavcodec/mpeg4audio.h"
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#include "libavutil/opt.h"
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static const AVOption options[] = {
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{"smc-interval", "StreamMuxConfig interval.",
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offsetof(LATMContext, mod), AV_OPT_TYPE_INT, {.dbl = 0x0014}, 0x0001, 0xffff, AV_OPT_FLAG_ENCODING_PARAM},
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static const AVClass latm_muxer_class = {
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.class_name = "LATM/LOAS muxer",
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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static int latm_decode_extradata(LATMContext *ctx, uint8_t *buf, int size)
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MPEG4AudioConfig m4ac;
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init_get_bits(&gb, buf, size * 8);
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ctx->off = avpriv_mpeg4audio_get_config(&m4ac, buf, size * 8, 1);
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skip_bits_long(&gb, ctx->off);
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/* FIXME: are any formats not allowed in LATM? */
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if (m4ac.object_type > AOT_SBR && m4ac.object_type != AOT_ALS) {
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av_log(ctx, AV_LOG_ERROR, "Muxing MPEG-4 AOT %d in LATM is not supported\n", m4ac.object_type);
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return AVERROR_INVALIDDATA;
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ctx->channel_conf = m4ac.chan_config;
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ctx->object_type = m4ac.object_type;
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static int latm_write_header(AVFormatContext *s)
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LATMContext *ctx = s->priv_data;
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AVCodecContext *avctx = s->streams[0]->codec;
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if (avctx->extradata_size > 0 &&
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latm_decode_extradata(ctx, avctx->extradata, avctx->extradata_size) < 0)
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return AVERROR_INVALIDDATA;
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static int latm_write_frame_header(AVFormatContext *s, PutBitContext *bs)
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LATMContext *ctx = s->priv_data;
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AVCodecContext *avctx = s->streams[0]->codec;
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put_bits(bs, 1, !!ctx->counter);
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init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);
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put_bits(bs, 1, 0); /* audioMuxVersion */
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put_bits(bs, 1, 1); /* allStreamsSameTimeFraming */
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put_bits(bs, 6, 0); /* numSubFrames */
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put_bits(bs, 4, 0); /* numProgram */
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put_bits(bs, 3, 0); /* numLayer */
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/* AudioSpecificConfig */
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if (ctx->object_type == AOT_ALS) {
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header_size = avctx->extradata_size-(ctx->off + 7) >> 3;
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avpriv_copy_bits(bs, &avctx->extradata[ctx->off], header_size);
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avpriv_copy_bits(bs, avctx->extradata, ctx->off + 3);
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if (!ctx->channel_conf) {
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avpriv_copy_pce_data(bs, &gb);
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put_bits(bs, 3, 0); /* frameLengthType */
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put_bits(bs, 8, 0xff); /* latmBufferFullness */
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put_bits(bs, 1, 0); /* otherDataPresent */
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put_bits(bs, 1, 0); /* crcCheckPresent */
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ctx->counter %= ctx->mod;
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static int latm_write_packet(AVFormatContext *s, AVPacket *pkt)
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AVIOContext *pb = s->pb;
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uint8_t loas_header[] = "\x56\xe0\x00";
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if (pkt->size > 2 && pkt->data[0] == 0xff && (pkt->data[1] >> 4) == 0xf) {
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av_log(s, AV_LOG_ERROR, "ADTS header detected - ADTS will not be incorrectly muxed into LATM\n");
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return AVERROR_INVALIDDATA;
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buf = av_malloc(pkt->size+1024);
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return AVERROR(ENOMEM);
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init_put_bits(&bs, buf, pkt->size+1024);
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latm_write_frame_header(s, &bs);
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/* PayloadLengthInfo() */
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for (i = 0; i <= pkt->size-255; i+=255)
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put_bits(&bs, 8, 255);
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put_bits(&bs, 8, pkt->size-i);
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/* The LATM payload is written unaligned */
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for (i = 0; i < pkt->size; i++)
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put_bits(&bs, 8, pkt->data[i]);
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avpriv_align_put_bits(&bs);
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len = put_bits_count(&bs) >> 3;
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loas_header[1] |= (len >> 8) & 0x1f;
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loas_header[2] |= len & 0xff;
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avio_write(pb, loas_header, 3);
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avio_write(pb, buf, len);
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AVOutputFormat ff_latm_muxer = {
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.long_name = NULL_IF_CONFIG_SMALL("LOAS/LATM"),
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.mime_type = "audio/MP4A-LATM",
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.extensions = "latm",
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.priv_data_size = sizeof(LATMContext),
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.audio_codec = CODEC_ID_AAC,
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.video_codec = CODEC_ID_NONE,
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.write_header = latm_write_header,
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.write_packet = latm_write_packet,
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.priv_class = &latm_muxer_class,