/*

 * RTP AMR Depacketizer, RFC 3267

 * 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 "libavutil/channel_layout.h"

#include "avformat.h"

#include "rtpdec_formats.h"

#include "libavutil/avstring.h"

static const uint8_t frame_sizes_nb[16] = {

    12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0

};

static const uint8_t frame_sizes_wb[16] = {

    17, 23, 32, 36, 40, 46, 50, 58, 60, 5, 5, 0, 0, 0, 0, 0

};

struct PayloadContext {

    int octet_align;

    int crc;

    int interleaving;

    int channels;

};

static av_cold int amr_init(AVFormatContext *s, int st_index, PayloadContext *data)

{

    data->channels = 1;

    return 0;

}

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

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

                             const uint8_t *buf, int len, uint16_t seq,

                             int flags)

{

    const uint8_t *frame_sizes = NULL;

    int frames;

    int i, ret;

    const uint8_t *speech_data;

    uint8_t *ptr;

    if (st->codecpar->codec_id == AV_CODEC_ID_AMR_NB) {

        frame_sizes = frame_sizes_nb;

    } else if (st->codecpar->codec_id == AV_CODEC_ID_AMR_WB) {

        frame_sizes = frame_sizes_wb;

    } else {

        av_log(ctx, AV_LOG_ERROR, "Bad codec ID\n");

        return AVERROR_INVALIDDATA;

    }

    if (st->codecpar->ch_layout.nb_channels != 1) {

        av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n");

        return AVERROR_INVALIDDATA;

    }

    av_channel_layout_default(&st->codecpar->ch_layout, 1);

    /* The AMR RTP packet consists of one header byte, followed

     * by one TOC byte for each AMR frame in the packet, followed

     * by the speech data for all the AMR frames.

     *

     * The header byte contains only a codec mode request, for

     * requesting what kind of AMR data the sender wants to

     * receive. Not used at the moment.

     */

    /* Count the number of frames in the packet. The highest bit

     * is set in a TOC byte if there are more frames following.

     */

    for (frames = 1; frames < len && (buf[frames] & 0x80); frames++) ;

    if (1 + frames >= len) {

        /* We hit the end of the packet while counting frames. */

        av_log(ctx, AV_LOG_ERROR, "No speech data found\n");

        return AVERROR_INVALIDDATA;

    }

    speech_data = buf + 1 + frames;

    /* Everything except the codec mode request byte should be output. */

    if ((ret = av_new_packet(pkt, len - 1)) < 0) {

        av_log(ctx, AV_LOG_ERROR, "Out of memory\n");

        return ret;

    }

    pkt->stream_index = st->index;

    ptr = pkt->data;

    for (i = 0; i < frames; i++) {

        uint8_t toc = buf[1 + i];

        int frame_size = frame_sizes[(toc >> 3) & 0x0f];

        if (speech_data + frame_size > buf + len) {

            /* Too little speech data */

            av_log(ctx, AV_LOG_WARNING, "Too little speech data in the RTP packet\n");

            /* Set the unwritten part of the packet to zero. */

            memset(ptr, 0, pkt->data + pkt->size - ptr);

            pkt->size = ptr - pkt->data;

            return 0;

        }

        /* Extract the AMR frame mode from the TOC byte */

        *ptr++ = toc & 0x7C;

        /* Copy the speech data */

        memcpy(ptr, speech_data, frame_size);

        speech_data += frame_size;

        ptr += frame_size;

    }

    if (speech_data < buf + len) {

        av_log(ctx, AV_LOG_WARNING, "Too much speech data in the RTP packet?\n");

        /* Set the unwritten part of the packet to zero. */

        memset(ptr, 0, pkt->data + pkt->size - ptr);

        pkt->size = ptr - pkt->data;

    }

    return 0;

}

static int amr_parse_fmtp(AVFormatContext *s,

                          AVStream *stream, PayloadContext *data,

                          const char *attr, const char *value)

{

    /* Some AMR SDP configurations contain "octet-align", without

     * the trailing =1. Therefore, if the value is empty,

     * interpret it as "1".

     */

    if (!strcmp(value, "")) {

        av_log(s, AV_LOG_WARNING, "AMR fmtp attribute %s had "

                                  "nonstandard empty value\n", attr);

        value = "1";

    }

    if (!strcmp(attr, "octet-align"))

        data->octet_align = atoi(value);

    else if (!strcmp(attr, "crc"))

        data->crc = atoi(value);

    else if (!strcmp(attr, "interleaving"))

        data->interleaving = atoi(value);

    else if (!strcmp(attr, "channels"))

        data->channels = atoi(value);

    return 0;

}

static int amr_parse_sdp_line(AVFormatContext *s, int st_index,

                              PayloadContext *data, const char *line)

{

    const char *p;

    int ret;

    if (st_index < 0)

        return 0;

    /* Parse an fmtp line this one:

     * a=fmtp:97 octet-align=1; interleaving=0

     * That is, a normal fmtp: line followed by semicolon & space

     * separated key/value pairs.

     */

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

        ret = ff_parse_fmtp(s, s->streams[st_index], data, p, amr_parse_fmtp);

        if (!data->octet_align || data->crc ||

            data->interleaving || data->channels != 1) {

            av_log(s, AV_LOG_ERROR, "Unsupported RTP/AMR configuration!\n");

            return -1;

        }

        return ret;

    }

    return 0;

}

const RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = {

    .enc_name         = "AMR",

    .codec_type       = AVMEDIA_TYPE_AUDIO,

    .codec_id         = AV_CODEC_ID_AMR_NB,

    .priv_data_size   = sizeof(PayloadContext),

    .init             = amr_init,

    .parse_sdp_a_line = amr_parse_sdp_line,

    .parse_packet     = amr_handle_packet,

};

const RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = {

    .enc_name         = "AMR-WB",

    .codec_type       = AVMEDIA_TYPE_AUDIO,

    .codec_id         = AV_CODEC_ID_AMR_WB,

    .priv_data_size   = sizeof(PayloadContext),

    .init             = amr_init,

    .parse_sdp_a_line = amr_parse_sdp_line,

    .parse_packet     = amr_handle_packet,

};