yading@11: /*
yading@11:  * RTP AMR Depacketizer, RFC 3267
yading@11:  * Copyright (c) 2010 Martin Storsjo
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/channel_layout.h"
yading@11: #include "avformat.h"
yading@11: #include "rtpdec_formats.h"
yading@11: #include "libavutil/avstring.h"
yading@11: 
yading@11: static const uint8_t frame_sizes_nb[16] = {
yading@11:     12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
yading@11: };
yading@11: static const uint8_t frame_sizes_wb[16] = {
yading@11:     17, 23, 32, 36, 40, 46, 50, 58, 60, 5, 5, 0, 0, 0, 0, 0
yading@11: };
yading@11: 
yading@11: struct PayloadContext {
yading@11:     int octet_align;
yading@11:     int crc;
yading@11:     int interleaving;
yading@11:     int channels;
yading@11: };
yading@11: 
yading@11: static PayloadContext *amr_new_context(void)
yading@11: {
yading@11:     PayloadContext *data = av_mallocz(sizeof(PayloadContext));
yading@11:     if(!data) return data;
yading@11:     data->channels = 1;
yading@11:     return data;
yading@11: }
yading@11: 
yading@11: static void amr_free_context(PayloadContext *data)
yading@11: {
yading@11:     av_free(data);
yading@11: }
yading@11: 
yading@11: static int amr_handle_packet(AVFormatContext *ctx, PayloadContext *data,
yading@11:                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
yading@11:                              const uint8_t *buf, int len, uint16_t seq,
yading@11:                              int flags)
yading@11: {
yading@11:     const uint8_t *frame_sizes = NULL;
yading@11:     int frames;
yading@11:     int i;
yading@11:     const uint8_t *speech_data;
yading@11:     uint8_t *ptr;
yading@11: 
yading@11:     if (st->codec->codec_id == AV_CODEC_ID_AMR_NB) {
yading@11:         frame_sizes = frame_sizes_nb;
yading@11:     } else if (st->codec->codec_id == AV_CODEC_ID_AMR_WB) {
yading@11:         frame_sizes = frame_sizes_wb;
yading@11:     } else {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Bad codec ID\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11: 
yading@11:     if (st->codec->channels != 1) {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11:     st->codec->channel_layout = AV_CH_LAYOUT_MONO;
yading@11: 
yading@11:     /* The AMR RTP packet consists of one header byte, followed
yading@11:      * by one TOC byte for each AMR frame in the packet, followed
yading@11:      * by the speech data for all the AMR frames.
yading@11:      *
yading@11:      * The header byte contains only a codec mode request, for
yading@11:      * requesting what kind of AMR data the sender wants to
yading@11:      * receive. Not used at the moment.
yading@11:      */
yading@11: 
yading@11:     /* Count the number of frames in the packet. The highest bit
yading@11:      * is set in a TOC byte if there are more frames following.
yading@11:      */
yading@11:     for (frames = 1; frames < len && (buf[frames] & 0x80); frames++) ;
yading@11: 
yading@11:     if (1 + frames >= len) {
yading@11:         /* We hit the end of the packet while counting frames. */
yading@11:         av_log(ctx, AV_LOG_ERROR, "No speech data found\n");
yading@11:         return AVERROR_INVALIDDATA;
yading@11:     }
yading@11: 
yading@11:     speech_data = buf + 1 + frames;
yading@11: 
yading@11:     /* Everything except the codec mode request byte should be output. */
yading@11:     if (av_new_packet(pkt, len - 1)) {
yading@11:         av_log(ctx, AV_LOG_ERROR, "Out of memory\n");
yading@11:         return AVERROR(ENOMEM);
yading@11:     }
yading@11:     pkt->stream_index = st->index;
yading@11:     ptr = pkt->data;
yading@11: 
yading@11:     for (i = 0; i < frames; i++) {
yading@11:         uint8_t toc = buf[1 + i];
yading@11:         int frame_size = frame_sizes[(toc >> 3) & 0x0f];
yading@11: 
yading@11:         if (speech_data + frame_size > buf + len) {
yading@11:             /* Too little speech data */
yading@11:             av_log(ctx, AV_LOG_WARNING, "Too little speech data in the RTP packet\n");
yading@11:             /* Set the unwritten part of the packet to zero. */
yading@11:             memset(ptr, 0, pkt->data + pkt->size - ptr);
yading@11:             pkt->size = ptr - pkt->data;
yading@11:             return 0;
yading@11:         }
yading@11: 
yading@11:         /* Extract the AMR frame mode from the TOC byte */
yading@11:         *ptr++ = toc & 0x7C;
yading@11: 
yading@11:         /* Copy the speech data */
yading@11:         memcpy(ptr, speech_data, frame_size);
yading@11:         speech_data += frame_size;
yading@11:         ptr += frame_size;
yading@11:     }
yading@11: 
yading@11:     if (speech_data < buf + len) {
yading@11:         av_log(ctx, AV_LOG_WARNING, "Too much speech data in the RTP packet?\n");
yading@11:         /* Set the unwritten part of the packet to zero. */
yading@11:         memset(ptr, 0, pkt->data + pkt->size - ptr);
yading@11:         pkt->size = ptr - pkt->data;
yading@11:     }
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int amr_parse_fmtp(AVStream *stream, PayloadContext *data,
yading@11:                           char *attr, char *value)
yading@11: {
yading@11:     /* Some AMR SDP configurations contain "octet-align", without
yading@11:      * the trailing =1. Therefore, if the value is empty,
yading@11:      * interpret it as "1".
yading@11:      */
yading@11:     if (!strcmp(value, "")) {
yading@11:         av_log(NULL, AV_LOG_WARNING, "AMR fmtp attribute %s had "
yading@11:                                      "nonstandard empty value\n", attr);
yading@11:         strcpy(value, "1");
yading@11:     }
yading@11:     if (!strcmp(attr, "octet-align"))
yading@11:         data->octet_align = atoi(value);
yading@11:     else if (!strcmp(attr, "crc"))
yading@11:         data->crc = atoi(value);
yading@11:     else if (!strcmp(attr, "interleaving"))
yading@11:         data->interleaving = atoi(value);
yading@11:     else if (!strcmp(attr, "channels"))
yading@11:         data->channels = atoi(value);
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int amr_parse_sdp_line(AVFormatContext *s, int st_index,
yading@11:                               PayloadContext *data, const char *line)
yading@11: {
yading@11:     const char *p;
yading@11:     int ret;
yading@11: 
yading@11:     if (st_index < 0)
yading@11:         return 0;
yading@11: 
yading@11:     /* Parse an fmtp line this one:
yading@11:      * a=fmtp:97 octet-align=1; interleaving=0
yading@11:      * That is, a normal fmtp: line followed by semicolon & space
yading@11:      * separated key/value pairs.
yading@11:      */
yading@11:     if (av_strstart(line, "fmtp:", &p)) {
yading@11:         ret = ff_parse_fmtp(s->streams[st_index], data, p, amr_parse_fmtp);
yading@11:         if (!data->octet_align || data->crc ||
yading@11:             data->interleaving || data->channels != 1) {
yading@11:             av_log(s, AV_LOG_ERROR, "Unsupported RTP/AMR configuration!\n");
yading@11:             return -1;
yading@11:         }
yading@11:         return ret;
yading@11:     }
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = {
yading@11:     .enc_name         = "AMR",
yading@11:     .codec_type       = AVMEDIA_TYPE_AUDIO,
yading@11:     .codec_id         = AV_CODEC_ID_AMR_NB,
yading@11:     .parse_sdp_a_line = amr_parse_sdp_line,
yading@11:     .alloc            = amr_new_context,
yading@11:     .free             = amr_free_context,
yading@11:     .parse_packet     = amr_handle_packet,
yading@11: };
yading@11: 
yading@11: RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = {
yading@11:     .enc_name         = "AMR-WB",
yading@11:     .codec_type       = AVMEDIA_TYPE_AUDIO,
yading@11:     .codec_id         = AV_CODEC_ID_AMR_WB,
yading@11:     .parse_sdp_a_line = amr_parse_sdp_line,
yading@11:     .alloc            = amr_new_context,
yading@11:     .free             = amr_free_context,
yading@11:     .parse_packet     = amr_handle_packet,
yading@11: };