1/* 2 * RTP VP8 Depacketizer 3 * Copyright (c) 2010 Josh Allmann 4 * 5 * This file is part of Libav. 6 * 7 * Libav is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * Libav is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with Libav; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22/** 23 * @file 24 * @brief RTP support for the VP8 payload 25 * @author Josh Allmann <joshua.allmann@gmail.com> 26 * @see http://www.webmproject.org/code/specs/rtp/ 27 */ 28 29#include "libavcodec/bytestream.h" 30 31#include "rtpdec_formats.h" 32 33struct PayloadContext { 34 AVIOContext *data; 35 uint32_t timestamp; 36 int is_keyframe; 37}; 38 39static void prepare_packet(AVPacket *pkt, PayloadContext *vp8, int stream) 40{ 41 av_init_packet(pkt); 42 pkt->stream_index = stream; 43 pkt->flags = vp8->is_keyframe ? AV_PKT_FLAG_KEY : 0; 44 pkt->size = avio_close_dyn_buf(vp8->data, &pkt->data); 45 pkt->destruct = av_destruct_packet; 46 vp8->data = NULL; 47} 48 49static int vp8_handle_packet(AVFormatContext *ctx, 50 PayloadContext *vp8, 51 AVStream *st, 52 AVPacket *pkt, 53 uint32_t *timestamp, 54 const uint8_t *buf, 55 int len, int flags) 56{ 57 int start_packet, end_packet, has_au, ret = AVERROR(EAGAIN); 58 59 if (!buf) { 60 // only called when vp8_handle_packet returns 1 61 if (!vp8->data) { 62 av_log(ctx, AV_LOG_ERROR, "Invalid VP8 data passed\n"); 63 return AVERROR_INVALIDDATA; 64 } 65 prepare_packet(pkt, vp8, st->index); 66 *timestamp = vp8->timestamp; 67 return 0; 68 } 69 70 start_packet = *buf & 1; 71 end_packet = flags & RTP_FLAG_MARKER; 72 has_au = *buf & 2; 73 buf++; 74 len--; 75 76 if (start_packet) { 77 int res; 78 uint32_t ts = *timestamp; 79 if (vp8->data) { 80 // missing end marker; return old frame anyway. untested 81 prepare_packet(pkt, vp8, st->index); 82 *timestamp = vp8->timestamp; // reset timestamp from old frame 83 84 // if current frame fits into one rtp packet, need to hold 85 // that for the next av_get_packet call 86 ret = end_packet ? 1 : 0; 87 } 88 if ((res = avio_open_dyn_buf(&vp8->data)) < 0) 89 return res; 90 vp8->is_keyframe = *buf & 1; 91 vp8->timestamp = ts; 92 } 93 94 if (!vp8->data || vp8->timestamp != *timestamp && ret == AVERROR(EAGAIN)) { 95 av_log(ctx, AV_LOG_WARNING, 96 "Received no start marker; dropping frame\n"); 97 return AVERROR(EAGAIN); 98 } 99 100 // cycle through VP8AU headers if needed 101 // not tested with actual VP8AUs 102 while (len) { 103 int au_len = len; 104 if (has_au && len > 2) { 105 au_len = AV_RB16(buf); 106 buf += 2; 107 len -= 2; 108 if (buf + au_len > buf + len) { 109 av_log(ctx, AV_LOG_ERROR, "Invalid VP8AU length\n"); 110 return AVERROR_INVALIDDATA; 111 } 112 } 113 114 avio_write(vp8->data, buf, au_len); 115 buf += au_len; 116 len -= au_len; 117 } 118 119 if (ret != AVERROR(EAGAIN)) // did we miss a end marker? 120 return ret; 121 122 if (end_packet) { 123 prepare_packet(pkt, vp8, st->index); 124 return 0; 125 } 126 127 return AVERROR(EAGAIN); 128} 129 130static PayloadContext *vp8_new_context(void) 131{ 132 av_log(NULL, AV_LOG_ERROR, "RTP VP8 payload implementation is incompatible " 133 "with the latest spec drafts.\n"); 134 return av_mallocz(sizeof(PayloadContext)); 135} 136 137static void vp8_free_context(PayloadContext *vp8) 138{ 139 if (vp8->data) { 140 uint8_t *tmp; 141 avio_close_dyn_buf(vp8->data, &tmp); 142 av_free(tmp); 143 } 144 av_free(vp8); 145} 146 147RTPDynamicProtocolHandler ff_vp8_dynamic_handler = { 148 .enc_name = "VP8", 149 .codec_type = AVMEDIA_TYPE_VIDEO, 150 .codec_id = CODEC_ID_VP8, 151 .alloc = vp8_new_context, 152 .free = vp8_free_context, 153 .parse_packet = vp8_handle_packet, 154}; 155