ffmpeg / libavformat / rtpdec_amr.c @ 2874c81c
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/*
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* RTP AMR Depacketizer, RFC 3267
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* Copyright (c) 2010 Martin Storsjo
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avformat.h" |
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#include "rtpdec_amr.h" |
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#include "libavutil/avstring.h" |
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static const uint8_t frame_sizes_nb[16] = { |
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12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 |
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}; |
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static const uint8_t frame_sizes_wb[16] = { |
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17, 23, 32, 36, 40, 46, 50, 58, 60, 5, 5, 0, 0, 0, 0, 0 |
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}; |
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static int amr_handle_packet(AVFormatContext *ctx, |
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PayloadContext *data, |
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AVStream *st, |
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AVPacket * pkt, |
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uint32_t * timestamp, |
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const uint8_t * buf,
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int len, int flags) |
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{ |
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const uint8_t *frame_sizes = NULL; |
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int frames;
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int i;
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const uint8_t *speech_data;
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uint8_t *ptr; |
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if (st->codec->codec_id == CODEC_ID_AMR_NB) {
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frame_sizes = frame_sizes_nb; |
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} else if (st->codec->codec_id == CODEC_ID_AMR_WB) { |
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frame_sizes = frame_sizes_wb; |
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} else {
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av_log(ctx, AV_LOG_ERROR, "Bad codec ID\n");
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return AVERROR_INVALIDDATA;
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} |
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if (st->codec->channels != 1) { |
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av_log(ctx, AV_LOG_ERROR, "Only mono AMR is supported\n");
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return AVERROR_INVALIDDATA;
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} |
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/* The AMR RTP packet consists of one header byte, followed
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* by one TOC byte for each AMR frame in the packet, followed
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* by the speech data for all the AMR frames.
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*
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* The header byte contains only a codec mode request, for
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* requesting what kind of AMR data the sender wants to
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* receive. Not used at the moment.
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*/
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/* Count the number of frames in the packet. The highest bit
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* is set in a TOC byte if there are more frames following.
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*/
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for (frames = 1; frames < len && (buf[frames] & 0x80); frames++) ; |
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if (1 + frames >= len) { |
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/* We hit the end of the packet while counting frames. */
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av_log(ctx, AV_LOG_ERROR, "No speech data found\n");
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return AVERROR_INVALIDDATA;
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} |
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speech_data = buf + 1 + frames;
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/* Everything except the codec mode request byte should be output. */
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if (av_new_packet(pkt, len - 1)) { |
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av_log(ctx, AV_LOG_ERROR, "Out of memory\n");
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return AVERROR(ENOMEM);
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} |
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pkt->stream_index = st->index; |
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ptr = pkt->data; |
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for (i = 0; i < frames; i++) { |
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uint8_t toc = buf[1 + i];
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int frame_size = frame_sizes[(toc >> 3) & 0x0f]; |
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if (speech_data + frame_size > buf + len) {
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/* Too little speech data */
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av_log(ctx, AV_LOG_WARNING, "Too little speech data in the RTP packet\n");
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/* Set the unwritten part of the packet to zero. */
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memset(ptr, 0, pkt->data + pkt->size - ptr);
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pkt->size = ptr - pkt->data; |
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return 0; |
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} |
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/* Extract the AMR frame mode from the TOC byte */
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*ptr++ = toc & 0x7C;
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/* Copy the speech data */
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memcpy(ptr, speech_data, frame_size); |
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speech_data += frame_size; |
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ptr += frame_size; |
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} |
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if (speech_data < buf + len) {
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av_log(ctx, AV_LOG_WARNING, "Too much speech data in the RTP packet?\n");
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/* Set the unwritten part of the packet to zero. */
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memset(ptr, 0, pkt->data + pkt->size - ptr);
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pkt->size = ptr - pkt->data; |
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} |
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return 0; |
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} |
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static int amr_parse_sdp_line(AVFormatContext *s, int st_index, |
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PayloadContext *data, const char *line) |
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{ |
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const char *p; |
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char attr[25], value[25]; |
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/* Parse an fmtp line this one:
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* a=fmtp:97 octet-align=1; interleaving=0
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* That is, a normal fmtp: line followed by semicolon & space
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* separated key/value pairs.
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*/
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if (av_strstart(line, "fmtp:", &p)) { |
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int octet_align = 0; |
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int crc = 0; |
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int interleaving = 0; |
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int channels = 1; |
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while (*p && *p == ' ') p++; /* strip spaces */ |
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while (*p && *p != ' ') p++; /* eat protocol identifier */ |
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while (*p && *p == ' ') p++; /* strip trailing spaces */ |
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while (ff_rtsp_next_attr_and_value(&p, attr, sizeof(attr), value, sizeof(value))) { |
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/* Some AMR SDP configurations contain "octet-align", without
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* the trailing =1. Therefore, if the value is empty,
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* interpret it as "1".
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*/
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if (!strcmp(value, "")) { |
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av_log(s, AV_LOG_WARNING, "AMR fmtp attribute %s had "
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"nonstandard empty value\n", attr);
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strcpy(value, "1");
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} |
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if (!strcmp(attr, "octet-align")) |
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octet_align = atoi(value); |
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else if (!strcmp(attr, "crc")) |
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crc = atoi(value); |
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else if (!strcmp(attr, "interleaving")) |
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interleaving = atoi(value); |
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else if (!strcmp(attr, "channels")) |
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channels = atoi(value); |
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} |
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if (!octet_align || crc || interleaving || channels != 1) { |
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av_log(s, AV_LOG_ERROR, "Unsupported RTP/AMR configuration!\n");
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return -1; |
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} |
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} |
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return 0; |
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} |
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RTPDynamicProtocolHandler ff_amr_nb_dynamic_handler = { |
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.enc_name = "AMR",
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.codec_type = AVMEDIA_TYPE_AUDIO, |
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.codec_id = CODEC_ID_AMR_NB, |
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.parse_sdp_a_line = amr_parse_sdp_line, |
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.parse_packet = amr_handle_packet, |
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}; |
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RTPDynamicProtocolHandler ff_amr_wb_dynamic_handler = { |
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.enc_name = "AMR-WB",
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.codec_type = AVMEDIA_TYPE_AUDIO, |
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.codec_id = CODEC_ID_AMR_WB, |
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.parse_sdp_a_line = amr_parse_sdp_line, |
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.parse_packet = amr_handle_packet, |
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}; |
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