/*
  * 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 PayloadContext *amr_new_context(void)
 {
     PayloadContext *data = av_mallocz(sizeof(PayloadContext));
     if(!data) return data;
     data->channels = 1;
     return data;
 }
 
 static void amr_free_context(PayloadContext *data)
 {
     av_free(data);
 }
 

 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;
     const uint8_t *speech_data;
     uint8_t *ptr;
 

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

         frame_sizes = frame_sizes_nb;

     } else if (st->codec->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->codec->channels != 1) {
         av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n");
         return AVERROR_INVALIDDATA;
     }

     st->codec->channel_layout = AV_CH_LAYOUT_MONO;

 
     /* 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 (av_new_packet(pkt, len - 1)) {
         av_log(ctx, AV_LOG_ERROR, "Out of memory\n");

         return AVERROR(ENOMEM);

     }
     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(AVStream *stream, PayloadContext *data,
                           char *attr, 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(NULL, AV_LOG_WARNING, "AMR fmtp attribute %s had "
                                      "nonstandard empty value\n", attr);
         strcpy(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->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;
 }
 
 RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = {
     .enc_name         = "AMR",

     .codec_type       = AVMEDIA_TYPE_AUDIO,

     .codec_id         = AV_CODEC_ID_AMR_NB,

     .parse_sdp_a_line = amr_parse_sdp_line,

     .alloc            = amr_new_context,
     .free             = amr_free_context,

     .parse_packet     = amr_handle_packet,
 };
 
 RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = {
     .enc_name         = "AMR-WB",

     .codec_type       = AVMEDIA_TYPE_AUDIO,

     .codec_id         = AV_CODEC_ID_AMR_WB,

     .parse_sdp_a_line = amr_parse_sdp_line,

     .alloc            = amr_new_context,
     .free             = amr_free_context,

     .parse_packet     = amr_handle_packet,
 };