Libav 0.7.1
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00001 /* 00002 * RTP AMR Depacketizer, RFC 3267 00003 * Copyright (c) 2010 Martin Storsjo 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * Libav is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00022 #include "avformat.h" 00023 #include "rtpdec_formats.h" 00024 #include "libavutil/avstring.h" 00025 00026 static const uint8_t frame_sizes_nb[16] = { 00027 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 00028 }; 00029 static const uint8_t frame_sizes_wb[16] = { 00030 17, 23, 32, 36, 40, 46, 50, 58, 60, 5, 5, 0, 0, 0, 0, 0 00031 }; 00032 00033 struct PayloadContext { 00034 int octet_align; 00035 int crc; 00036 int interleaving; 00037 int channels; 00038 }; 00039 00040 static PayloadContext *amr_new_context(void) 00041 { 00042 PayloadContext *data = av_mallocz(sizeof(PayloadContext)); 00043 if(!data) return data; 00044 data->channels = 1; 00045 return data; 00046 } 00047 00048 static void amr_free_context(PayloadContext *data) 00049 { 00050 av_free(data); 00051 } 00052 00053 static int amr_handle_packet(AVFormatContext *ctx, 00054 PayloadContext *data, 00055 AVStream *st, 00056 AVPacket * pkt, 00057 uint32_t * timestamp, 00058 const uint8_t * buf, 00059 int len, int flags) 00060 { 00061 const uint8_t *frame_sizes = NULL; 00062 int frames; 00063 int i; 00064 const uint8_t *speech_data; 00065 uint8_t *ptr; 00066 00067 if (st->codec->codec_id == CODEC_ID_AMR_NB) { 00068 frame_sizes = frame_sizes_nb; 00069 } else if (st->codec->codec_id == CODEC_ID_AMR_WB) { 00070 frame_sizes = frame_sizes_wb; 00071 } else { 00072 av_log(ctx, AV_LOG_ERROR, "Bad codec ID\n"); 00073 return AVERROR_INVALIDDATA; 00074 } 00075 00076 if (st->codec->channels != 1) { 00077 av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n"); 00078 return AVERROR_INVALIDDATA; 00079 } 00080 00081 /* The AMR RTP packet consists of one header byte, followed 00082 * by one TOC byte for each AMR frame in the packet, followed 00083 * by the speech data for all the AMR frames. 00084 * 00085 * The header byte contains only a codec mode request, for 00086 * requesting what kind of AMR data the sender wants to 00087 * receive. Not used at the moment. 00088 */ 00089 00090 /* Count the number of frames in the packet. The highest bit 00091 * is set in a TOC byte if there are more frames following. 00092 */ 00093 for (frames = 1; frames < len && (buf[frames] & 0x80); frames++) ; 00094 00095 if (1 + frames >= len) { 00096 /* We hit the end of the packet while counting frames. */ 00097 av_log(ctx, AV_LOG_ERROR, "No speech data found\n"); 00098 return AVERROR_INVALIDDATA; 00099 } 00100 00101 speech_data = buf + 1 + frames; 00102 00103 /* Everything except the codec mode request byte should be output. */ 00104 if (av_new_packet(pkt, len - 1)) { 00105 av_log(ctx, AV_LOG_ERROR, "Out of memory\n"); 00106 return AVERROR(ENOMEM); 00107 } 00108 pkt->stream_index = st->index; 00109 ptr = pkt->data; 00110 00111 for (i = 0; i < frames; i++) { 00112 uint8_t toc = buf[1 + i]; 00113 int frame_size = frame_sizes[(toc >> 3) & 0x0f]; 00114 00115 if (speech_data + frame_size > buf + len) { 00116 /* Too little speech data */ 00117 av_log(ctx, AV_LOG_WARNING, "Too little speech data in the RTP packet\n"); 00118 /* Set the unwritten part of the packet to zero. */ 00119 memset(ptr, 0, pkt->data + pkt->size - ptr); 00120 pkt->size = ptr - pkt->data; 00121 return 0; 00122 } 00123 00124 /* Extract the AMR frame mode from the TOC byte */ 00125 *ptr++ = toc & 0x7C; 00126 00127 /* Copy the speech data */ 00128 memcpy(ptr, speech_data, frame_size); 00129 speech_data += frame_size; 00130 ptr += frame_size; 00131 } 00132 00133 if (speech_data < buf + len) { 00134 av_log(ctx, AV_LOG_WARNING, "Too much speech data in the RTP packet?\n"); 00135 /* Set the unwritten part of the packet to zero. */ 00136 memset(ptr, 0, pkt->data + pkt->size - ptr); 00137 pkt->size = ptr - pkt->data; 00138 } 00139 00140 return 0; 00141 } 00142 00143 static int amr_parse_fmtp(AVStream *stream, PayloadContext *data, 00144 char *attr, char *value) 00145 { 00146 /* Some AMR SDP configurations contain "octet-align", without 00147 * the trailing =1. Therefore, if the value is empty, 00148 * interpret it as "1". 00149 */ 00150 if (!strcmp(value, "")) { 00151 av_log(NULL, AV_LOG_WARNING, "AMR fmtp attribute %s had " 00152 "nonstandard empty value\n", attr); 00153 strcpy(value, "1"); 00154 } 00155 if (!strcmp(attr, "octet-align")) 00156 data->octet_align = atoi(value); 00157 else if (!strcmp(attr, "crc")) 00158 data->crc = atoi(value); 00159 else if (!strcmp(attr, "interleaving")) 00160 data->interleaving = atoi(value); 00161 else if (!strcmp(attr, "channels")) 00162 data->channels = atoi(value); 00163 return 0; 00164 } 00165 00166 static int amr_parse_sdp_line(AVFormatContext *s, int st_index, 00167 PayloadContext *data, const char *line) 00168 { 00169 const char *p; 00170 int ret; 00171 00172 /* Parse an fmtp line this one: 00173 * a=fmtp:97 octet-align=1; interleaving=0 00174 * That is, a normal fmtp: line followed by semicolon & space 00175 * separated key/value pairs. 00176 */ 00177 if (av_strstart(line, "fmtp:", &p)) { 00178 ret = ff_parse_fmtp(s->streams[st_index], data, p, amr_parse_fmtp); 00179 if (!data->octet_align || data->crc || 00180 data->interleaving || data->channels != 1) { 00181 av_log(s, AV_LOG_ERROR, "Unsupported RTP/AMR configuration!\n"); 00182 return -1; 00183 } 00184 return ret; 00185 } 00186 return 0; 00187 } 00188 00189 RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = { 00190 .enc_name = "AMR", 00191 .codec_type = AVMEDIA_TYPE_AUDIO, 00192 .codec_id = CODEC_ID_AMR_NB, 00193 .parse_sdp_a_line = amr_parse_sdp_line, 00194 .alloc = amr_new_context, 00195 .free = amr_free_context, 00196 .parse_packet = amr_handle_packet, 00197 }; 00198 00199 RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = { 00200 .enc_name = "AMR-WB", 00201 .codec_type = AVMEDIA_TYPE_AUDIO, 00202 .codec_id = CODEC_ID_AMR_WB, 00203 .parse_sdp_a_line = amr_parse_sdp_line, 00204 .alloc = amr_new_context, 00205 .free = amr_free_context, 00206 .parse_packet = amr_handle_packet, 00207 }; 00208