FFmpeg: libavformat/movenchint.c Source File

00001 /*
00002  * MOV, 3GP, MP4 muxer RTP hinting
00003  * Copyright (c) 2010 Martin Storsjo
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "movenc.h"
00023 #include "libavutil/intreadwrite.h"
00024 #include "internal.h"
00025 #include "rtpenc_chain.h"
00026 #include "avio_internal.h"
00027 
00028 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
00029 {
00030     MOVMuxContext *mov  = s->priv_data;
00031     MOVTrack *track     = &mov->tracks[index];
00032     MOVTrack *src_track = &mov->tracks[src_index];
00033     AVStream *src_st    = s->streams[src_index];
00034     int ret = AVERROR(ENOMEM);
00035 
00036     track->tag = MKTAG('r','t','p',' ');
00037     track->src_track = src_index;
00038 
00039     track->enc = avcodec_alloc_context3(NULL);
00040     if (!track->enc)
00041         goto fail;
00042     track->enc->codec_type = AVMEDIA_TYPE_DATA;
00043     track->enc->codec_tag  = track->tag;
00044 
00045     track->rtp_ctx = ff_rtp_chain_mux_open(s, src_st, NULL,
00046                                            RTP_MAX_PACKET_SIZE);
00047     if (!track->rtp_ctx)
00048         goto fail;
00049 
00050     /* Copy the RTP AVStream timebase back to the hint AVStream */
00051     track->timescale = track->rtp_ctx->streams[0]->time_base.den;
00052 
00053     /* Mark the hinted track that packets written to it should be
00054      * sent to this track for hinting. */
00055     src_track->hint_track = index;
00056     return 0;
00057 fail:
00058     av_log(s, AV_LOG_WARNING,
00059            "Unable to initialize hinting of stream %d\n", src_index);
00060     av_freep(&track->enc);
00061     /* Set a default timescale, to avoid crashes in av_dump_format */
00062     track->timescale = 90000;
00063     return ret;
00064 }
00065 
00069 static void sample_queue_pop(HintSampleQueue *queue)
00070 {
00071     if (queue->len <= 0)
00072         return;
00073     if (queue->samples[0].own_data)
00074         av_free(queue->samples[0].data);
00075     queue->len--;
00076     memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
00077 }
00078 
00082 static void sample_queue_free(HintSampleQueue *queue)
00083 {
00084     int i;
00085     for (i = 0; i < queue->len; i++)
00086         if (queue->samples[i].own_data)
00087             av_free(queue->samples[i].data);
00088     av_freep(&queue->samples);
00089     queue->len = 0;
00090     queue->size = 0;
00091 }
00092 
00098 static void sample_queue_push(HintSampleQueue *queue, uint8_t *data, int size,
00099                               int sample)
00100 {
00101     /* No need to keep track of smaller samples, since describing them
00102      * with immediates is more efficient. */
00103     if (size <= 14)
00104         return;
00105     if (!queue->samples || queue->len >= queue->size) {
00106         HintSample* samples;
00107         queue->size += 10;
00108         samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
00109         if (!samples)
00110             return;
00111         queue->samples = samples;
00112     }
00113     queue->samples[queue->len].data = data;
00114     queue->samples[queue->len].size = size;
00115     queue->samples[queue->len].sample_number = sample;
00116     queue->samples[queue->len].offset = 0;
00117     queue->samples[queue->len].own_data = 0;
00118     queue->len++;
00119 }
00120 
00124 static void sample_queue_retain(HintSampleQueue *queue)
00125 {
00126     int i;
00127     for (i = 0; i < queue->len; ) {
00128         HintSample *sample = &queue->samples[i];
00129         if (!sample->own_data) {
00130             uint8_t* ptr = av_malloc(sample->size);
00131             if (!ptr) {
00132                 /* Unable to allocate memory for this one, remove it */
00133                 memmove(queue->samples + i, queue->samples + i + 1,
00134                         sizeof(HintSample)*(queue->len - i - 1));
00135                 queue->len--;
00136                 continue;
00137             }
00138             memcpy(ptr, sample->data, sample->size);
00139             sample->data = ptr;
00140             sample->own_data = 1;
00141         }
00142         i++;
00143     }
00144 }
00145 
00162 static int match_segments(const uint8_t *haystack, int h_len,
00163                           const uint8_t *needle, int n_pos, int n_len,
00164                           int *match_h_offset_ptr, int *match_n_offset_ptr,
00165                           int *match_len_ptr)
00166 {
00167     int h_pos;
00168     for (h_pos = 0; h_pos < h_len; h_pos++) {
00169         int match_len = 0;
00170         int match_h_pos, match_n_pos;
00171 
00172         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
00173         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
00174                needle[n_pos + match_len] == haystack[h_pos + match_len])
00175             match_len++;
00176         if (match_len <= 8)
00177             continue;
00178 
00179         /* If a sufficiently large match was found, try to expand
00180          * the matched segment backwards. */
00181         match_h_pos = h_pos;
00182         match_n_pos = n_pos;
00183         while (match_n_pos > 0 && match_h_pos > 0 &&
00184                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
00185             match_n_pos--;
00186             match_h_pos--;
00187             match_len++;
00188         }
00189         if (match_len <= 14)
00190             continue;
00191         *match_h_offset_ptr = match_h_pos;
00192         *match_n_offset_ptr = match_n_pos;
00193         *match_len_ptr = match_len;
00194         return 0;
00195     }
00196     return -1;
00197 }
00198 
00214 static int find_sample_match(const uint8_t *data, int len,
00215                              HintSampleQueue *queue, int *pos,
00216                              int *match_sample, int *match_offset,
00217                              int *match_len)
00218 {
00219     while (queue->len > 0) {
00220         HintSample *sample = &queue->samples[0];
00221         /* If looking for matches in a new sample, skip the first 5 bytes,
00222          * since they often may be modified/removed in the output packet. */
00223         if (sample->offset == 0 && sample->size > 5)
00224             sample->offset = 5;
00225 
00226         if (match_segments(data, len, sample->data, sample->offset,
00227                            sample->size, pos, match_offset, match_len) == 0) {
00228             *match_sample = sample->sample_number;
00229             /* Next time, look for matches at this offset, with a little
00230              * margin to this match. */
00231             sample->offset = *match_offset + *match_len + 5;
00232             if (sample->offset + 10 >= sample->size)
00233                 sample_queue_pop(queue); /* Not enough useful data left */
00234             return 0;
00235         }
00236 
00237         if (sample->offset < 10 && sample->size > 20) {
00238             /* No match found from the start of the sample,
00239              * try from the middle of the sample instead. */
00240             sample->offset = sample->size/2;
00241         } else {
00242             /* No match for this sample, remove it */
00243             sample_queue_pop(queue);
00244         }
00245     }
00246     return -1;
00247 }
00248 
00249 static void output_immediate(const uint8_t *data, int size,
00250                              AVIOContext *out, int *entries)
00251 {
00252     while (size > 0) {
00253         int len = size;
00254         if (len > 14)
00255             len = 14;
00256         avio_w8(out, 1); /* immediate constructor */
00257         avio_w8(out, len); /* amount of valid data */
00258         avio_write(out, data, len);
00259         data += len;
00260         size -= len;
00261 
00262         for (; len < 14; len++)
00263             avio_w8(out, 0);
00264 
00265         (*entries)++;
00266     }
00267 }
00268 
00269 static void output_match(AVIOContext *out, int match_sample,
00270                          int match_offset, int match_len, int *entries)
00271 {
00272     avio_w8(out, 2); /* sample constructor */
00273     avio_w8(out, 0); /* track reference */
00274     avio_wb16(out, match_len);
00275     avio_wb32(out, match_sample);
00276     avio_wb32(out, match_offset);
00277     avio_wb16(out, 1); /* bytes per block */
00278     avio_wb16(out, 1); /* samples per block */
00279     (*entries)++;
00280 }
00281 
00282 static void describe_payload(const uint8_t *data, int size,
00283                              AVIOContext *out, int *entries,
00284                              HintSampleQueue *queue)
00285 {
00286     /* Describe the payload using different constructors */
00287     while (size > 0) {
00288         int match_sample, match_offset, match_len, pos;
00289         if (find_sample_match(data, size, queue, &pos, &match_sample,
00290                               &match_offset, &match_len) < 0)
00291             break;
00292         output_immediate(data, pos, out, entries);
00293         data += pos;
00294         size -= pos;
00295         output_match(out, match_sample, match_offset, match_len, entries);
00296         data += match_len;
00297         size -= match_len;
00298     }
00299     output_immediate(data, size, out, entries);
00300 }
00301 
00314 static int write_hint_packets(AVIOContext *out, const uint8_t *data,
00315                               int size, MOVTrack *trk, int64_t *pts)
00316 {
00317     int64_t curpos;
00318     int64_t count_pos, entries_pos;
00319     int count = 0, entries;
00320 
00321     count_pos = avio_tell(out);
00322     /* RTPsample header */
00323     avio_wb16(out, 0); /* packet count */
00324     avio_wb16(out, 0); /* reserved */
00325 
00326     while (size > 4) {
00327         uint32_t packet_len = AV_RB32(data);
00328         uint16_t seq;
00329         uint32_t ts;
00330 
00331         data += 4;
00332         size -= 4;
00333         if (packet_len > size || packet_len <= 12)
00334             break;
00335         if (data[1] >= 200 && data[1] <= 204) {
00336             /* RTCP packet, just skip */
00337             data += packet_len;
00338             size -= packet_len;
00339             continue;
00340         }
00341 
00342         if (packet_len > trk->max_packet_size)
00343             trk->max_packet_size = packet_len;
00344 
00345         seq = AV_RB16(&data[2]);
00346         ts = AV_RB32(&data[4]);
00347 
00348         if (trk->prev_rtp_ts == 0)
00349             trk->prev_rtp_ts = ts;
00350         /* Unwrap the 32-bit RTP timestamp that wraps around often
00351          * into a not (as often) wrapping 64-bit timestamp. */
00352         trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
00353         trk->prev_rtp_ts = ts;
00354         if (*pts == AV_NOPTS_VALUE)
00355             *pts = trk->cur_rtp_ts_unwrapped;
00356 
00357         count++;
00358         /* RTPpacket header */
00359         avio_wb32(out, 0); /* relative_time */
00360         avio_write(out, data, 2); /* RTP header */
00361         avio_wb16(out, seq); /* RTPsequenceseed */
00362         avio_wb16(out, 0); /* reserved + flags */
00363         entries_pos = avio_tell(out);
00364         avio_wb16(out, 0); /* entry count */
00365 
00366         data += 12;
00367         size -= 12;
00368         packet_len -= 12;
00369 
00370         entries = 0;
00371         /* Write one or more constructors describing the payload data */
00372         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
00373         data += packet_len;
00374         size -= packet_len;
00375 
00376         curpos = avio_tell(out);
00377         avio_seek(out, entries_pos, SEEK_SET);
00378         avio_wb16(out, entries);
00379         avio_seek(out, curpos, SEEK_SET);
00380     }
00381 
00382     curpos = avio_tell(out);
00383     avio_seek(out, count_pos, SEEK_SET);
00384     avio_wb16(out, count);
00385     avio_seek(out, curpos, SEEK_SET);
00386     return count;
00387 }
00388 
00389 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
00390                              int track_index, int sample,
00391                              uint8_t *sample_data, int sample_size)
00392 {
00393     MOVMuxContext *mov = s->priv_data;
00394     MOVTrack *trk = &mov->tracks[track_index];
00395     AVFormatContext *rtp_ctx = trk->rtp_ctx;
00396     uint8_t *buf = NULL;
00397     int size;
00398     AVIOContext *hintbuf = NULL;
00399     AVPacket hint_pkt;
00400     int ret = 0, count;
00401 
00402     if (!rtp_ctx)
00403         return AVERROR(ENOENT);
00404     if (!rtp_ctx->pb)
00405         return AVERROR(ENOMEM);
00406 
00407     if (sample_data)
00408         sample_queue_push(&trk->sample_queue, sample_data, sample_size, sample);
00409     else
00410         sample_queue_push(&trk->sample_queue, pkt->data, pkt->size, sample);
00411 
00412     /* Feed the packet to the RTP muxer */
00413     ff_write_chained(rtp_ctx, 0, pkt, s);
00414 
00415     /* Fetch the output from the RTP muxer, open a new output buffer
00416      * for next time. */
00417     size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
00418     if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
00419                                        RTP_MAX_PACKET_SIZE)) < 0)
00420         goto done;
00421 
00422     if (size <= 0)
00423         goto done;
00424 
00425     /* Open a buffer for writing the hint */
00426     if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
00427         goto done;
00428     av_init_packet(&hint_pkt);
00429     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
00430     av_freep(&buf);
00431 
00432     /* Write the hint data into the hint track */
00433     hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
00434     hint_pkt.data = buf;
00435     hint_pkt.pts  = hint_pkt.dts;
00436     hint_pkt.stream_index = track_index;
00437     if (pkt->flags & AV_PKT_FLAG_KEY)
00438         hint_pkt.flags |= AV_PKT_FLAG_KEY;
00439     if (count > 0)
00440         ff_mov_write_packet(s, &hint_pkt);
00441 done:
00442     av_free(buf);
00443     sample_queue_retain(&trk->sample_queue);
00444     return ret;
00445 }
00446 
00447 void ff_mov_close_hinting(MOVTrack *track) {
00448     AVFormatContext* rtp_ctx = track->rtp_ctx;
00449     uint8_t *ptr;
00450 
00451     av_freep(&track->enc);
00452     sample_queue_free(&track->sample_queue);
00453     if (!rtp_ctx)
00454         return;
00455     if (rtp_ctx->pb) {
00456         av_write_trailer(rtp_ctx);
00457         avio_close_dyn_buf(rtp_ctx->pb, &ptr);
00458         av_free(ptr);
00459     }
00460     avformat_free_context(rtp_ctx);
00461 }
00462