2 * MOV, 3GP, MP4 muxer RTP hinting
3 * Copyright (c) 2010 Martin Storsjo
5 * This file is part of FFmpeg.
7 * FFmpeg 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.
12 * FFmpeg 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "libavutil/intreadwrite.h"
25 #include "rtpenc_chain.h"
26 #include "avio_internal.h"
28 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
30 MOVMuxContext *mov = s->priv_data;
31 MOVTrack *track = &mov->tracks[index];
32 MOVTrack *src_track = &mov->tracks[src_index];
33 AVStream *src_st = s->streams[src_index];
34 int ret = AVERROR(ENOMEM);
36 track->tag = MKTAG('r','t','p',' ');
37 track->src_track = src_index;
39 track->enc = avcodec_alloc_context();
42 track->enc->codec_type = AVMEDIA_TYPE_DATA;
43 track->enc->codec_tag = track->tag;
45 track->rtp_ctx = ff_rtp_chain_mux_open(s, src_st, NULL,
50 /* Copy the RTP AVStream timebase back to the hint AVStream */
51 track->timescale = track->rtp_ctx->streams[0]->time_base.den;
53 /* Mark the hinted track that packets written to it should be
54 * sent to this track for hinting. */
55 src_track->hint_track = index;
58 av_log(s, AV_LOG_WARNING,
59 "Unable to initialize hinting of stream %d\n", src_index);
60 av_freep(&track->enc);
61 /* Set a default timescale, to avoid crashes in av_dump_format */
62 track->timescale = 90000;
67 * Remove the first sample from the sample queue.
69 static void sample_queue_pop(HintSampleQueue *queue)
73 if (queue->samples[0].own_data)
74 av_free(queue->samples[0].data);
76 memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
80 * Empty the sample queue, releasing all memory.
82 static void sample_queue_free(HintSampleQueue *queue)
85 for (i = 0; i < queue->len; i++)
86 if (queue->samples[i].own_data)
87 av_free(queue->samples[i].data);
88 av_freep(&queue->samples);
94 * Add a reference to the sample data to the sample queue. The data is
95 * not copied. sample_queue_retain should be called before pkt->data
98 static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
100 /* No need to keep track of smaller samples, since describing them
101 * with immediates is more efficient. */
104 if (!queue->samples || queue->len >= queue->size) {
107 samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
110 queue->samples = samples;
112 queue->samples[queue->len].data = pkt->data;
113 queue->samples[queue->len].size = pkt->size;
114 queue->samples[queue->len].sample_number = sample;
115 queue->samples[queue->len].offset = 0;
116 queue->samples[queue->len].own_data = 0;
121 * Make local copies of all referenced sample data in the queue.
123 static void sample_queue_retain(HintSampleQueue *queue)
126 for (i = 0; i < queue->len; ) {
127 HintSample *sample = &queue->samples[i];
128 if (!sample->own_data) {
129 uint8_t* ptr = av_malloc(sample->size);
131 /* Unable to allocate memory for this one, remove it */
132 memmove(queue->samples + i, queue->samples + i + 1,
133 sizeof(HintSample)*(queue->len - i - 1));
137 memcpy(ptr, sample->data, sample->size);
139 sample->own_data = 1;
146 * Find matches of needle[n_pos ->] within haystack. If a sufficiently
147 * large match is found, matching bytes before n_pos are included
148 * in the match, too (within the limits of the arrays).
150 * @param haystack buffer that may contain parts of needle
151 * @param h_len length of the haystack buffer
152 * @param needle buffer containing source data that have been used to
154 * @param n_pos start position in needle used for looking for matches
155 * @param n_len length of the needle buffer
156 * @param match_h_offset_ptr offset of the first matching byte within haystack
157 * @param match_n_offset_ptr offset of the first matching byte within needle
158 * @param match_len_ptr length of the matched segment
159 * @return 0 if a match was found, < 0 if no match was found
161 static int match_segments(const uint8_t *haystack, int h_len,
162 const uint8_t *needle, int n_pos, int n_len,
163 int *match_h_offset_ptr, int *match_n_offset_ptr,
167 for (h_pos = 0; h_pos < h_len; h_pos++) {
169 int match_h_pos, match_n_pos;
171 /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
172 while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
173 needle[n_pos + match_len] == haystack[h_pos + match_len])
178 /* If a sufficiently large match was found, try to expand
179 * the matched segment backwards. */
182 while (match_n_pos > 0 && match_h_pos > 0 &&
183 needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
190 *match_h_offset_ptr = match_h_pos;
191 *match_n_offset_ptr = match_n_pos;
192 *match_len_ptr = match_len;
199 * Look for segments in samples in the sample queue matching the data
200 * in ptr. Samples not matching are removed from the queue. If a match
201 * is found, the next time it will look for matches starting from the
202 * end of the previous matched segment.
204 * @param data data to find matches for in the sample queue
205 * @param len length of the data buffer
206 * @param queue samples used for looking for matching segments
207 * @param pos the offset in data of the matched segment
208 * @param match_sample the number of the sample that contained the match
209 * @param match_offset the offset of the matched segment within the sample
210 * @param match_len the length of the matched segment
211 * @return 0 if a match was found, < 0 if no match was found
213 static int find_sample_match(const uint8_t *data, int len,
214 HintSampleQueue *queue, int *pos,
215 int *match_sample, int *match_offset,
218 while (queue->len > 0) {
219 HintSample *sample = &queue->samples[0];
220 /* If looking for matches in a new sample, skip the first 5 bytes,
221 * since they often may be modified/removed in the output packet. */
222 if (sample->offset == 0 && sample->size > 5)
225 if (match_segments(data, len, sample->data, sample->offset,
226 sample->size, pos, match_offset, match_len) == 0) {
227 *match_sample = sample->sample_number;
228 /* Next time, look for matches at this offset, with a little
229 * margin to this match. */
230 sample->offset = *match_offset + *match_len + 5;
231 if (sample->offset + 10 >= sample->size)
232 sample_queue_pop(queue); /* Not enough useful data left */
236 if (sample->offset < 10 && sample->size > 20) {
237 /* No match found from the start of the sample,
238 * try from the middle of the sample instead. */
239 sample->offset = sample->size/2;
241 /* No match for this sample, remove it */
242 sample_queue_pop(queue);
248 static void output_immediate(const uint8_t *data, int size,
249 AVIOContext *out, int *entries)
255 avio_w8(out, 1); /* immediate constructor */
256 avio_w8(out, len); /* amount of valid data */
257 avio_write(out, data, len);
261 for (; len < 14; len++)
268 static void output_match(AVIOContext *out, int match_sample,
269 int match_offset, int match_len, int *entries)
271 avio_w8(out, 2); /* sample constructor */
272 avio_w8(out, 0); /* track reference */
273 avio_wb16(out, match_len);
274 avio_wb32(out, match_sample);
275 avio_wb32(out, match_offset);
276 avio_wb16(out, 1); /* bytes per block */
277 avio_wb16(out, 1); /* samples per block */
281 static void describe_payload(const uint8_t *data, int size,
282 AVIOContext *out, int *entries,
283 HintSampleQueue *queue)
285 /* Describe the payload using different constructors */
287 int match_sample, match_offset, match_len, pos;
288 if (find_sample_match(data, size, queue, &pos, &match_sample,
289 &match_offset, &match_len) < 0)
291 output_immediate(data, pos, out, entries);
294 output_match(out, match_sample, match_offset, match_len, entries);
298 output_immediate(data, size, out, entries);
302 * Write an RTP hint (that may contain one or more RTP packets)
303 * for the packets in data. data contains one or more packets with a
306 * @param out buffer where the hints are written
307 * @param data buffer containing RTP packets
308 * @param size the size of the data buffer
309 * @param trk the MOVTrack for the hint track
310 * @param pts pointer where the timestamp for the written RTP hint is stored
311 * @return the number of RTP packets in the written hint
313 static int write_hint_packets(AVIOContext *out, const uint8_t *data,
314 int size, MOVTrack *trk, int64_t *pts)
317 int64_t count_pos, entries_pos;
318 int count = 0, entries;
320 count_pos = avio_tell(out);
321 /* RTPsample header */
322 avio_wb16(out, 0); /* packet count */
323 avio_wb16(out, 0); /* reserved */
326 uint32_t packet_len = AV_RB32(data);
332 if (packet_len > size || packet_len <= 12)
334 if (data[1] >= 200 && data[1] <= 204) {
335 /* RTCP packet, just skip */
341 if (packet_len > trk->max_packet_size)
342 trk->max_packet_size = packet_len;
344 seq = AV_RB16(&data[2]);
345 ts = AV_RB32(&data[4]);
347 if (trk->prev_rtp_ts == 0)
348 trk->prev_rtp_ts = ts;
349 /* Unwrap the 32-bit RTP timestamp that wraps around often
350 * into a not (as often) wrapping 64-bit timestamp. */
351 trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
352 trk->prev_rtp_ts = ts;
353 if (*pts == AV_NOPTS_VALUE)
354 *pts = trk->cur_rtp_ts_unwrapped;
357 /* RTPpacket header */
358 avio_wb32(out, 0); /* relative_time */
359 avio_write(out, data, 2); /* RTP header */
360 avio_wb16(out, seq); /* RTPsequenceseed */
361 avio_wb16(out, 0); /* reserved + flags */
362 entries_pos = avio_tell(out);
363 avio_wb16(out, 0); /* entry count */
370 /* Write one or more constructors describing the payload data */
371 describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
375 curpos = avio_tell(out);
376 avio_seek(out, entries_pos, SEEK_SET);
377 avio_wb16(out, entries);
378 avio_seek(out, curpos, SEEK_SET);
381 curpos = avio_tell(out);
382 avio_seek(out, count_pos, SEEK_SET);
383 avio_wb16(out, count);
384 avio_seek(out, curpos, SEEK_SET);
388 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
389 int track_index, int sample)
391 MOVMuxContext *mov = s->priv_data;
392 MOVTrack *trk = &mov->tracks[track_index];
393 AVFormatContext *rtp_ctx = trk->rtp_ctx;
396 AVIOContext *hintbuf = NULL;
401 return AVERROR(ENOENT);
403 return AVERROR(ENOMEM);
405 sample_queue_push(&trk->sample_queue, pkt, sample);
407 /* Feed the packet to the RTP muxer */
408 ff_write_chained(rtp_ctx, 0, pkt, s);
410 /* Fetch the output from the RTP muxer, open a new output buffer
412 size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
413 if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
414 RTP_MAX_PACKET_SIZE)) < 0)
420 /* Open a buffer for writing the hint */
421 if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
423 av_init_packet(&hint_pkt);
424 count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
427 /* Write the hint data into the hint track */
428 hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
430 hint_pkt.pts = hint_pkt.dts;
431 hint_pkt.stream_index = track_index;
432 if (pkt->flags & AV_PKT_FLAG_KEY)
433 hint_pkt.flags |= AV_PKT_FLAG_KEY;
435 ff_mov_write_packet(s, &hint_pkt);
438 sample_queue_retain(&trk->sample_queue);
442 void ff_mov_close_hinting(MOVTrack *track) {
443 AVFormatContext* rtp_ctx = track->rtp_ctx;
446 av_freep(&track->enc);
447 sample_queue_free(&track->sample_queue);
451 av_write_trailer(rtp_ctx);
452 avio_close_dyn_buf(rtp_ctx->pb, &ptr);
455 avformat_free_context(rtp_ctx);