aboutsummaryrefslogtreecommitdiffstats
path: root/libavformat/rtpdec_vp8.c
blob: 3db61c143e0f43b3fcc4619e35076d549afb830c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
/*
 * RTP VP8 Depacketizer
 * Copyright (c) 2010 Josh Allmann
 * Copyright (c) 2012 Martin Storsjo
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * @brief RTP support for the VP8 payload
 * @author Josh Allmann <joshua.allmann@gmail.com>
 * @see http://tools.ietf.org/html/draft-ietf-payload-vp8-05
 */

#include "libavcodec/bytestream.h"

#include "rtpdec_formats.h"

struct PayloadContext {
    AVIOContext *data;
    uint32_t     timestamp;
    int          is_keyframe;
    /* If sequence_ok is set, we keep returning data (even if we might have
     * lost some data, but we haven't lost any too critical data that would
     * cause the decoder to desynchronize and output random garbage).
     */
    int          sequence_ok;
    int          first_part_size;
    uint16_t     prev_seq;
    int          prev_pictureid;
    int          broken_frame;
    /* If sequence_dirty is set, we have lost some data (critical or
     * non-critical) and decoding will have some sort of artefacts, and
     * we thus should request a new keyframe.
     */
    int          sequence_dirty;
    int          got_keyframe;
};

static void vp8_free_buffer(PayloadContext *vp8)
{
    uint8_t *tmp;
    if (!vp8->data)
        return;
    avio_close_dyn_buf(vp8->data, &tmp);
    av_free(tmp);
    vp8->data = NULL;
}

static int vp8_broken_sequence(AVFormatContext *ctx, PayloadContext *vp8,
                               const char *msg)
{
    vp8->sequence_ok = 0;
    av_log(ctx, AV_LOG_WARNING, "%s", msg);
    vp8_free_buffer(vp8);
    return AVERROR(EAGAIN);
}

static int vp8_handle_packet(AVFormatContext *ctx, PayloadContext *vp8,
                             AVStream *st, AVPacket *pkt, uint32_t *timestamp,
                             const uint8_t *buf, int len, uint16_t seq,
                             int flags)
{
    int start_partition, end_packet;
    int extended_bits, part_id;
    int pictureid_present = 0, tl0picidx_present = 0, tid_present = 0,
        keyidx_present = 0;
    int pictureid = -1, pictureid_mask = 0;
    int returned_old_frame = 0;
    uint32_t old_timestamp;

    if (!buf) {
        if (vp8->data) {
            int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
            if (ret < 0)
                return ret;
            *timestamp = vp8->timestamp;
            if (vp8->sequence_dirty)
                pkt->flags |= AV_PKT_FLAG_CORRUPT;
            return 0;
        }
        return AVERROR(EAGAIN);
    }

    if (len < 1)
        return AVERROR_INVALIDDATA;

    extended_bits   = buf[0] & 0x80;
    start_partition = buf[0] & 0x10;
    part_id         = buf[0] & 0x0f;
    end_packet      = flags & RTP_FLAG_MARKER;
    buf++;
    len--;
    if (extended_bits) {
        if (len < 1)
            return AVERROR_INVALIDDATA;
        pictureid_present = buf[0] & 0x80;
        tl0picidx_present = buf[0] & 0x40;
        tid_present       = buf[0] & 0x20;
        keyidx_present    = buf[0] & 0x10;
        buf++;
        len--;
    }
    if (pictureid_present) {
        if (len < 1)
            return AVERROR_INVALIDDATA;
        if (buf[0] & 0x80) {
            if (len < 2)
                return AVERROR_INVALIDDATA;
            pictureid = AV_RB16(buf) & 0x7fff;
            pictureid_mask = 0x7fff;
            buf += 2;
            len -= 2;
        } else {
            pictureid = buf[0] & 0x7f;
            pictureid_mask = 0x7f;
            buf++;
            len--;
        }
    }
    if (tl0picidx_present) {
        // Ignoring temporal level zero index
        buf++;
        len--;
    }
    if (tid_present || keyidx_present) {
        // Ignoring temporal layer index, layer sync bit and keyframe index
        buf++;
        len--;
    }
    if (len < 1)
        return AVERROR_INVALIDDATA;

    if (start_partition && part_id == 0 && len >= 3) {
        int res;
        int non_key = buf[0] & 0x01;
        if (!non_key) {
            vp8_free_buffer(vp8);
            // Keyframe, decoding ok again
            vp8->sequence_ok = 1;
            vp8->sequence_dirty = 0;
            vp8->got_keyframe = 1;
        } else {
            int can_continue = vp8->data && !vp8->is_keyframe &&
                               avio_tell(vp8->data) >= vp8->first_part_size;
            if (!vp8->sequence_ok)
                return AVERROR(EAGAIN);
            if (!vp8->got_keyframe)
                return vp8_broken_sequence(ctx, vp8, "Keyframe missing\n");
            if (pictureid >= 0) {
                if (pictureid != ((vp8->prev_pictureid + 1) & pictureid_mask)) {
                    return vp8_broken_sequence(ctx, vp8,
                                               "Missed a picture, sequence broken\n");
                } else {
                    if (vp8->data && !can_continue)
                        return vp8_broken_sequence(ctx, vp8,
                                                   "Missed a picture, sequence broken\n");
                }
            } else {
                uint16_t expected_seq = vp8->prev_seq + 1;
                int16_t diff = seq - expected_seq;
                if (vp8->data) {
                    // No picture id, so we can't know if missed packets
                    // contained any new frames. If diff == 0, we did get
                    // later packets from the same frame (matching timestamp),
                    // so we know we didn't miss any frame. If diff == 1 and
                    // we still have data (not flushed by the end of frame
                    // marker), the single missed packet must have been part
                    // of the same frame.
                    if ((diff == 0 || diff == 1) && can_continue) {
                        // Proceed with what we have
                    } else {
                        return vp8_broken_sequence(ctx, vp8,
                                                   "Missed too much, sequence broken\n");
                    }
                } else {
                    if (diff != 0)
                        return vp8_broken_sequence(ctx, vp8,
                                                   "Missed unknown data, sequence broken\n");
                }
            }
            if (vp8->data) {
                vp8->sequence_dirty = 1;
                if (avio_tell(vp8->data) >= vp8->first_part_size) {
                    int ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
                    if (ret < 0)
                        return ret;
                    pkt->flags |= AV_PKT_FLAG_CORRUPT;
                    returned_old_frame = 1;
                    old_timestamp = vp8->timestamp;
                } else {
                    // Shouldn't happen
                    vp8_free_buffer(vp8);
                }
            }
        }
        vp8->first_part_size = (AV_RL16(&buf[1]) << 3 | buf[0] >> 5) + 3;
        if ((res = avio_open_dyn_buf(&vp8->data)) < 0)
            return res;
        vp8->timestamp = *timestamp;
        vp8->broken_frame = 0;
        vp8->prev_pictureid = pictureid;
        vp8->is_keyframe = !non_key;
    } else {
        uint16_t expected_seq = vp8->prev_seq + 1;

        if (!vp8->sequence_ok)
            return AVERROR(EAGAIN);

        if (vp8->timestamp != *timestamp) {
            // Missed the start of the new frame, sequence broken
            return vp8_broken_sequence(ctx, vp8,
                                       "Received no start marker; dropping frame\n");
        }

        if (seq != expected_seq) {
            if (vp8->is_keyframe) {
                return vp8_broken_sequence(ctx, vp8,
                                           "Missed part of a keyframe, sequence broken\n");
            } else if (vp8->data && avio_tell(vp8->data) >= vp8->first_part_size) {
                vp8->broken_frame = 1;
                vp8->sequence_dirty = 1;
            } else {
                return vp8_broken_sequence(ctx, vp8,
                                           "Missed part of the first partition, sequence broken\n");
            }
        }
    }

    if (!vp8->data)
        return vp8_broken_sequence(ctx, vp8, "Received no start marker\n");

    vp8->prev_seq = seq;
    if (!vp8->broken_frame)
        avio_write(vp8->data, buf, len);

    if (returned_old_frame) {
        *timestamp = old_timestamp;
        return end_packet ? 1 : 0;
    }

    if (end_packet) {
        int ret;
        ret = ff_rtp_finalize_packet(pkt, &vp8->data, st->index);
        if (ret < 0)
            return ret;
        if (vp8->sequence_dirty)
            pkt->flags |= AV_PKT_FLAG_CORRUPT;
        return 0;
    }

    return AVERROR(EAGAIN);
}

static PayloadContext *vp8_new_context(void)
{
    PayloadContext *vp8 = av_mallocz(sizeof(PayloadContext));
    if (!vp8)
        return NULL;
    vp8->sequence_ok = 1;
    return vp8;
}

static void vp8_free_context(PayloadContext *vp8)
{
    vp8_free_buffer(vp8);
    av_free(vp8);
}

static int vp8_need_keyframe(PayloadContext *vp8)
{
    return vp8->sequence_dirty || !vp8->sequence_ok;
}

RTPDynamicProtocolHandler ff_vp8_dynamic_handler = {
    .enc_name       = "VP8",
    .codec_type     = AVMEDIA_TYPE_VIDEO,
    .codec_id       = AV_CODEC_ID_VP8,
    .alloc          = vp8_new_context,
    .free           = vp8_free_context,
    .parse_packet   = vp8_handle_packet,
    .need_keyframe  = vp8_need_keyframe,
};