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/*

 * RTP Depacketization of MP4A-LATM, RFC 3016

 * Copyright (c) 2010 Martin Storsjo

 *

 * 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 "rtpdec_formats.h"

#include "internal.h"

#include "libavutil/avstring.h"

#include "libavcodec/get_bits.h"

struct PayloadContext {

    AVIOContext *dyn_buf;

    uint8_t *buf;

    int pos, len;

    uint32_t timestamp;

};

static PayloadContext *latm_new_context(void)

{

    return av_mallocz(sizeof(PayloadContext));

}

static void latm_free_context(PayloadContext *data)

{

    if (!data)

        return;

    if (data->dyn_buf) {

        uint8_t *p;

        avio_close_dyn_buf(data->dyn_buf, &p);

        av_free(p);

    }

    av_free(data->buf);

    av_free(data);

}

static int latm_parse_packet(AVFormatContext *ctx, PayloadContext *data,

                             AVStream *st, AVPacket *pkt, uint32_t *timestamp,

                             const uint8_t *buf, int len, uint16_t seq,

                             int flags)

{

    int ret, cur_len;

    if (buf) {

        if (!data->dyn_buf || data->timestamp != *timestamp) {

            av_freep(&data->buf);

            if (data->dyn_buf)

                avio_close_dyn_buf(data->dyn_buf, &data->buf);

            data->dyn_buf = NULL;

            av_freep(&data->buf);

            data->timestamp = *timestamp;

            if ((ret = avio_open_dyn_buf(&data->dyn_buf)) < 0)

                return ret;

        }

        avio_write(data->dyn_buf, buf, len);

        if (!(flags & RTP_FLAG_MARKER))

            return AVERROR(EAGAIN);

        av_free(data->buf);

        data->len = avio_close_dyn_buf(data->dyn_buf, &data->buf);

        data->dyn_buf = NULL;

        data->pos = 0;

    }

    if (!data->buf) {

        av_log(ctx, AV_LOG_ERROR, "No data available yet\n");

        return AVERROR(EIO);

    }

    cur_len = 0;

    while (data->pos < data->len) {

        uint8_t val = data->buf[data->pos++];

        cur_len += val;

        if (val != 0xff)

            break;

    }

    if (data->pos + cur_len > data->len) {

        av_log(ctx, AV_LOG_ERROR, "Malformed LATM packet\n");

        return AVERROR(EIO);

    }

    if ((ret = av_new_packet(pkt, cur_len)) < 0)

        return ret;

    memcpy(pkt->data, data->buf + data->pos, cur_len);

    data->pos += cur_len;

    pkt->stream_index = st->index;

    return data->pos < data->len;

}

static int parse_fmtp_config(AVStream *st, char *value)

{

    int len = ff_hex_to_data(NULL, value), i, ret = 0;

    GetBitContext gb;

    uint8_t *config;

    int audio_mux_version, same_time_framing, num_programs, num_layers;

    /* Pad this buffer, too, to avoid out of bounds reads with get_bits below */

    config = av_mallocz(len + FF_INPUT_BUFFER_PADDING_SIZE);

    if (!config)

        return AVERROR(ENOMEM);

    ff_hex_to_data(config, value);

    init_get_bits(&gb, config, len*8);

    audio_mux_version = get_bits(&gb, 1);

    same_time_framing = get_bits(&gb, 1);

    skip_bits(&gb, 6); /* num_sub_frames */

    num_programs      = get_bits(&gb, 4);

    num_layers        = get_bits(&gb, 3);

    if (audio_mux_version != 0 || same_time_framing != 1 || num_programs != 0 ||

        num_layers != 0) {

        av_log(NULL, AV_LOG_WARNING, "Unsupported LATM config (%d,%d,%d,%d)\n",

                                     audio_mux_version, same_time_framing,

                                     num_programs, num_layers);

        ret = AVERROR_PATCHWELCOME;

        goto end;

    }

    av_freep(&st->codec->extradata);

    if (ff_alloc_extradata(st->codec, (get_bits_left(&gb) + 7)/8)) {

        ret = AVERROR(ENOMEM);

        goto end;

    }

    for (i = 0; i < st->codec->extradata_size; i++)

        st->codec->extradata[i] = get_bits(&gb, 8);

end:

    av_free(config);

    return ret;

}

static int parse_fmtp(AVStream *stream, PayloadContext *data,

                      char *attr, char *value)

{

    int res;

    if (!strcmp(attr, "config")) {

        res = parse_fmtp_config(stream, value);

        if (res < 0)

            return res;

    } else if (!strcmp(attr, "cpresent")) {

        int cpresent = atoi(value);

        if (cpresent != 0)

            avpriv_request_sample(NULL,

                                  "RTP MP4A-LATM with in-band configuration");

    }

    return 0;

}

static int latm_parse_sdp_line(AVFormatContext *s, int st_index,

                               PayloadContext *data, const char *line)

{

    const char *p;

    if (st_index < 0)

        return 0;

    if (av_strstart(line, "fmtp:", &p))

        return ff_parse_fmtp(s->streams[st_index], data, p, parse_fmtp);

    return 0;

}

RTPDynamicProtocolHandler ff_mp4a_latm_dynamic_handler = {

    .enc_name           = "MP4A-LATM",

    .codec_type         = AVMEDIA_TYPE_AUDIO,

    .codec_id           = AV_CODEC_ID_AAC,

    .parse_sdp_a_line   = latm_parse_sdp_line,

    .alloc              = latm_new_context,

    .free               = latm_free_context,

    .parse_packet       = latm_parse_packet

};