3 * Copyright (c) 2010 Josh Allmann
4 * Copyright (c) 2012 Martin Storsjo
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 * @brief RTP support for the VP8 payload
26 * @author Josh Allmann <joshua.allmann@gmail.com>
27 * @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
30 #include "libavcodec/bytestream.h"
32 #include "rtpdec_formats.h"
34 struct PayloadContext {
38 /* If sequence_ok is set, we keep returning data (even if we might have
39 * lost some data, but we haven't lost any too critical data that would
40 * cause the decoder to desynchronize and output random garbage).
47 /* If sequence_dirty is set, we have lost some data (critical or
48 * non-critical) and decoding will have some sort of artefacts, and
49 * we thus should request a new keyframe.
55 static void vp8_free_buffer(PayloadContext *vp8)
60 avio_close_dyn_buf(vp8->data, &tmp);
65 static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8,
69 av_log(ctx, AV_LOG_WARNING, "%s", msg);
71 return AVERROR(EAGAIN);
74 static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8,
75 AVStream *st, AVPacket *pkt, uint32_t *timestamp,
76 const uint8_t *buf, int len, uint16_t seq,
79 int start_partition, end_packet;
80 int extended_bits, part_id;
81 int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
83 int pictureid = -1, pictureid_mask = 0;
84 int returned_old_frame = 0;
85 uint32_t old_timestamp;
89 int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
92 *timestamp = vp8->timestamp;
95 return AVERROR(EAGAIN);
99 return AVERROR_INVALIDDATA;
101 extended_bits = buf[0] & 0x80;
102 start_partition = buf[0] & 0x10;
103 part_id = buf[0] & 0x0f;
104 end_packet = flags & RTP_FLAG_MARKER;
109 return AVERROR_INVALIDDATA;
110 pictureid_present = buf[0] & 0x80;
111 tl0picidx_present = buf[0] & 0x40;
112 tid_present = buf[0] & 0x20;
113 keyidx_present = buf[0] & 0x10;
117 if (pictureid_present) {
119 return AVERROR_INVALIDDATA;
122 return AVERROR_INVALIDDATA;
123 pictureid = AV_RB16(buf) & 0x7fff;
124 pictureid_mask = 0x7fff;
128 pictureid = buf[0] & 0x7f;
129 pictureid_mask = 0x7f;
134 if (tl0picidx_present) {
135 // Ignoring temporal level zero index
139 if (tid_present || keyidx_present) {
140 // Ignoring temporal layer index, layer sync bit and keyframe index
145 return AVERROR_INVALIDDATA;
147 if (start_partition && part_id == 0 && len >= 3) {
149 int non_key = buf[0] & 0x01;
151 vp8_free_buffer(vp8);
152 // Keyframe, decoding ok again
153 vp8->sequence_ok = 1;
154 vp8->sequence_dirty = 0;
155 vp8->got_keyframe = 1;
157 int can_continue = vp8->data && !vp8->is_keyframe &&
158 avio_tell(vp8->data) >= vp8->first_part_size;
159 if (!vp8->sequence_ok)
160 return AVERROR(EAGAIN);
161 if (!vp8->got_keyframe)
162 return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n");
163 if (pictureid >= 0) {
164 if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) {
165 return vp8_broken_sequence(ctx, vp8,
166 "Missed a picture, sequence broken\n");
168 if (vp8->data && !can_continue)
169 return vp8_broken_sequence(ctx, vp8,
170 "Missed a picture, sequence broken\n");
173 uint16_t expected_seq = vp8->prev_seq + 1;
174 int16_t diff = seq - expected_seq;
176 // No picture id, so we can't know if missed packets
177 // contained any new frames. If diff == 0, we did get
178 // later packets from the same frame (matching timestamp),
179 // so we know we didn't miss any frame. If diff == 1 and
180 // we still have data (not flushed by the end of frame
181 // marker), the single missed packet must have been part
182 // of the same frame.
183 if ((diff == 0 || diff == 1) && can_continue) {
184 // Proceed with what we have
186 return vp8_broken_sequence(ctx, vp8,
187 "Missed too much, sequence broken\n");
191 return vp8_broken_sequence(ctx, vp8,
192 "Missed unknown data, sequence broken\n");
196 vp8->sequence_dirty = 1;
197 if (avio_tell(vp8->data) >= vp8->first_part_size) {
198 int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
201 pkt->size = vp8->first_part_size;
202 returned_old_frame = 1;
203 old_timestamp = vp8->timestamp;
206 vp8_free_buffer(vp8);
210 vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3;
211 if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
213 vp8->timestamp = *timestamp;
214 vp8->broken_frame = 0;
215 vp8->prev_pictureid = pictureid;
216 vp8->is_keyframe = !non_key;
218 uint16_t expected_seq = vp8->prev_seq + 1;
220 if (!vp8->sequence_ok)
221 return AVERROR(EAGAIN);
223 if (vp8->timestamp != *timestamp) {
224 // Missed the start of the new frame, sequence broken
225 vp8->sequence_ok = 0;
226 av_log(ctx, AV_LOG_WARNING,
227 "Received no start marker; dropping frame\n");
228 vp8_free_buffer(vp8);
229 return AVERROR(EAGAIN);
232 if (seq != expected_seq) {
233 if (vp8->is_keyframe) {
234 return vp8_broken_sequence(ctx, vp8,
235 "Missed part of a keyframe, sequence broken\n");
236 } else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) {
237 vp8->broken_frame = 1;
238 vp8->sequence_dirty = 1;
240 return vp8_broken_sequence(ctx, vp8,
241 "Missed part of the first partition, sequence broken\n");
247 return vp8_broken_sequence(ctx, vp8, "Received no start marker\n");
250 avio_write(vp8->data, buf, len);
252 if (returned_old_frame) {
253 *timestamp = old_timestamp;
254 return end_packet ? 1 : 0;
259 ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
262 if (vp8->broken_frame)
263 pkt->size = vp8->first_part_size;
267 return AVERROR(EAGAIN);
270 static PayloadContext *vp8_new_context(void)
272 PayloadContext *vp8 = av_mallocz(sizeof(PayloadContext));
275 vp8->sequence_ok = 1;
279 static void vp8_free_context(PayloadContext *vp8)
281 vp8_free_buffer(vp8);
285 static int vp8_need_keyframe(PayloadContext *vp8)
287 return vp8->sequence_dirty || !vp8->sequence_ok;
290 RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
292 .codec_type = AVMEDIA_TYPE_VIDEO,
293 .codec_id = AV_CODEC_ID_VP8,
294 .alloc = vp8_new_context,
295 .free = vp8_free_context,
296 .parse_packet = vp8_handle_packet,
297 .need_keyframe = vp8_need_keyframe,