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_context();
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, AVPacket *pkt, int sample)
00099 {
00100     /* No need to keep track of smaller samples, since describing them
00101      * with immediates is more efficient. */
00102     if (pkt->size <= 14)
00103         return;
00104     if (!queue->samples || queue->len >= queue->size) {
00105         HintSample* samples;
00106         queue->size += 10;
00107         samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
00108         if (!samples)
00109             return;
00110         queue->samples = samples;
00111     }
00112     queue->samples[queue->len].data = pkt->data;
00113     queue->samples[queue->len].size = pkt->size;
00114     queue->samples[queue->len].sample_number = sample;
00115     queue->samples[queue->len].offset = 0;
00116     queue->samples[queue->len].own_data = 0;
00117     queue->len++;
00118 }
00119 
00123 static void sample_queue_retain(HintSampleQueue *queue)
00124 {
00125     int i;
00126     for (i = 0; i < queue->len; ) {
00127         HintSample *sample = &queue->samples[i];
00128         if (!sample->own_data) {
00129             uint8_t* ptr = av_malloc(sample->size);
00130             if (!ptr) {
00131                 /* Unable to allocate memory for this one, remove it */
00132                 memmove(queue->samples + i, queue->samples + i + 1,
00133                         sizeof(HintSample)*(queue->len - i - 1));
00134                 queue->len--;
00135                 continue;
00136             }
00137             memcpy(ptr, sample->data, sample->size);
00138             sample->data = ptr;
00139             sample->own_data = 1;
00140         }
00141         i++;
00142     }
00143 }
00144 
00161 static int match_segments(const uint8_t *haystack, int h_len,
00162                           const uint8_t *needle, int n_pos, int n_len,
00163                           int *match_h_offset_ptr, int *match_n_offset_ptr,
00164                           int *match_len_ptr)
00165 {
00166     int h_pos;
00167     for (h_pos = 0; h_pos < h_len; h_pos++) {
00168         int match_len = 0;
00169         int match_h_pos, match_n_pos;
00170 
00171         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
00172         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
00173                needle[n_pos + match_len] == haystack[h_pos + match_len])
00174             match_len++;
00175         if (match_len <= 8)
00176             continue;
00177 
00178         /* If a sufficiently large match was found, try to expand
00179          * the matched segment backwards. */
00180         match_h_pos = h_pos;
00181         match_n_pos = n_pos;
00182         while (match_n_pos > 0 && match_h_pos > 0 &&
00183                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
00184             match_n_pos--;
00185             match_h_pos--;
00186             match_len++;
00187         }
00188         if (match_len <= 14)
00189             continue;
00190         *match_h_offset_ptr = match_h_pos;
00191         *match_n_offset_ptr = match_n_pos;
00192         *match_len_ptr = match_len;
00193         return 0;
00194     }
00195     return -1;
00196 }
00197 
00213 static int find_sample_match(const uint8_t *data, int len,
00214                              HintSampleQueue *queue, int *pos,
00215                              int *match_sample, int *match_offset,
00216                              int *match_len)
00217 {
00218     while (queue->len > 0) {
00219         HintSample *sample = &queue->samples[0];
00220         /* If looking for matches in a new sample, skip the first 5 bytes,
00221          * since they often may be modified/removed in the output packet. */
00222         if (sample->offset == 0 && sample->size > 5)
00223             sample->offset = 5;
00224 
00225         if (match_segments(data, len, sample->data, sample->offset,
00226                            sample->size, pos, match_offset, match_len) == 0) {
00227             *match_sample = sample->sample_number;
00228             /* Next time, look for matches at this offset, with a little
00229              * margin to this match. */
00230             sample->offset = *match_offset + *match_len + 5;
00231             if (sample->offset + 10 >= sample->size)
00232                 sample_queue_pop(queue); /* Not enough useful data left */
00233             return 0;
00234         }
00235 
00236         if (sample->offset < 10 && sample->size > 20) {
00237             /* No match found from the start of the sample,
00238              * try from the middle of the sample instead. */
00239             sample->offset = sample->size/2;
00240         } else {
00241             /* No match for this sample, remove it */
00242             sample_queue_pop(queue);
00243         }
00244     }
00245     return -1;
00246 }
00247 
00248 static void output_immediate(const uint8_t *data, int size,
00249                              AVIOContext *out, int *entries)
00250 {
00251     while (size > 0) {
00252         int len = size;
00253         if (len > 14)
00254             len = 14;
00255         avio_w8(out, 1); /* immediate constructor */
00256         avio_w8(out, len); /* amount of valid data */
00257         avio_write(out, data, len);
00258         data += len;
00259         size -= len;
00260 
00261         for (; len < 14; len++)
00262             avio_w8(out, 0);
00263 
00264         (*entries)++;
00265     }
00266 }
00267 
00268 static void output_match(AVIOContext *out, int match_sample,
00269                          int match_offset, int match_len, int *entries)
00270 {
00271     avio_w8(out, 2); /* sample constructor */
00272     avio_w8(out, 0); /* track reference */
00273     avio_wb16(out, match_len);
00274     avio_wb32(out, match_sample);
00275     avio_wb32(out, match_offset);
00276     avio_wb16(out, 1); /* bytes per block */
00277     avio_wb16(out, 1); /* samples per block */
00278     (*entries)++;
00279 }
00280 
00281 static void describe_payload(const uint8_t *data, int size,
00282                              AVIOContext *out, int *entries,
00283                              HintSampleQueue *queue)
00284 {
00285     /* Describe the payload using different constructors */
00286     while (size > 0) {
00287         int match_sample, match_offset, match_len, pos;
00288         if (find_sample_match(data, size, queue, &pos, &match_sample,
00289                               &match_offset, &match_len) < 0)
00290             break;
00291         output_immediate(data, pos, out, entries);
00292         data += pos;
00293         size -= pos;
00294         output_match(out, match_sample, match_offset, match_len, entries);
00295         data += match_len;
00296         size -= match_len;
00297     }
00298     output_immediate(data, size, out, entries);
00299 }
00300 
00313 static int write_hint_packets(AVIOContext *out, const uint8_t *data,
00314                               int size, MOVTrack *trk, int64_t *pts)
00315 {
00316     int64_t curpos;
00317     int64_t count_pos, entries_pos;
00318     int count = 0, entries;
00319 
00320     count_pos = avio_tell(out);
00321     /* RTPsample header */
00322     avio_wb16(out, 0); /* packet count */
00323     avio_wb16(out, 0); /* reserved */
00324 
00325     while (size > 4) {
00326         uint32_t packet_len = AV_RB32(data);
00327         uint16_t seq;
00328         uint32_t ts;
00329 
00330         data += 4;
00331         size -= 4;
00332         if (packet_len > size || packet_len <= 12)
00333             break;
00334         if (data[1] >= 200 && data[1] <= 204) {
00335             /* RTCP packet, just skip */
00336             data += packet_len;
00337             size -= packet_len;
00338             continue;
00339         }
00340 
00341         if (packet_len > trk->max_packet_size)
00342             trk->max_packet_size = packet_len;
00343 
00344         seq = AV_RB16(&data[2]);
00345         ts = AV_RB32(&data[4]);
00346 
00347         if (trk->prev_rtp_ts == 0)
00348             trk->prev_rtp_ts = ts;
00349         /* Unwrap the 32-bit RTP timestamp that wraps around often
00350          * into a not (as often) wrapping 64-bit timestamp. */
00351         trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
00352         trk->prev_rtp_ts = ts;
00353         if (*pts == AV_NOPTS_VALUE)
00354             *pts = trk->cur_rtp_ts_unwrapped;
00355 
00356         count++;
00357         /* RTPpacket header */
00358         avio_wb32(out, 0); /* relative_time */
00359         avio_write(out, data, 2); /* RTP header */
00360         avio_wb16(out, seq); /* RTPsequenceseed */
00361         avio_wb16(out, 0); /* reserved + flags */
00362         entries_pos = avio_tell(out);
00363         avio_wb16(out, 0); /* entry count */
00364 
00365         data += 12;
00366         size -= 12;
00367         packet_len -= 12;
00368 
00369         entries = 0;
00370         /* Write one or more constructors describing the payload data */
00371         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
00372         data += packet_len;
00373         size -= packet_len;
00374 
00375         curpos = avio_tell(out);
00376         avio_seek(out, entries_pos, SEEK_SET);
00377         avio_wb16(out, entries);
00378         avio_seek(out, curpos, SEEK_SET);
00379     }
00380 
00381     curpos = avio_tell(out);
00382     avio_seek(out, count_pos, SEEK_SET);
00383     avio_wb16(out, count);
00384     avio_seek(out, curpos, SEEK_SET);
00385     return count;
00386 }
00387 
00388 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
00389                              int track_index, int sample)
00390 {
00391     MOVMuxContext *mov = s->priv_data;
00392     MOVTrack *trk = &mov->tracks[track_index];
00393     AVFormatContext *rtp_ctx = trk->rtp_ctx;
00394     uint8_t *buf = NULL;
00395     int size;
00396     AVIOContext *hintbuf = NULL;
00397     AVPacket hint_pkt;
00398     int ret = 0, count;
00399 
00400     if (!rtp_ctx)
00401         return AVERROR(ENOENT);
00402     if (!rtp_ctx->pb)
00403         return AVERROR(ENOMEM);
00404 
00405     sample_queue_push(&trk->sample_queue, pkt, sample);
00406 
00407     /* Feed the packet to the RTP muxer */
00408     ff_write_chained(rtp_ctx, 0, pkt, s);
00409 
00410     /* Fetch the output from the RTP muxer, open a new output buffer
00411      * for next time. */
00412     size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
00413     if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
00414                                        RTP_MAX_PACKET_SIZE)) < 0)
00415         goto done;
00416 
00417     if (size <= 0)
00418         goto done;
00419 
00420     /* Open a buffer for writing the hint */
00421     if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
00422         goto done;
00423     av_init_packet(&hint_pkt);
00424     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
00425     av_freep(&buf);
00426 
00427     /* Write the hint data into the hint track */
00428     hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
00429     hint_pkt.data = buf;
00430     hint_pkt.pts  = hint_pkt.dts;
00431     hint_pkt.stream_index = track_index;
00432     if (pkt->flags & AV_PKT_FLAG_KEY)
00433         hint_pkt.flags |= AV_PKT_FLAG_KEY;
00434     if (count > 0)
00435         ff_mov_write_packet(s, &hint_pkt);
00436 done:
00437     av_free(buf);
00438     sample_queue_retain(&trk->sample_queue);
00439     return ret;
00440 }
00441 
00442 void ff_mov_close_hinting(MOVTrack *track) {
00443     AVFormatContext* rtp_ctx = track->rtp_ctx;
00444     uint8_t *ptr;
00445 
00446     av_freep(&track->enc);
00447     sample_queue_free(&track->sample_queue);
00448     if (!rtp_ctx)
00449         return;
00450     if (rtp_ctx->pb) {
00451         av_write_trailer(rtp_ctx);
00452         avio_close_dyn_buf(rtp_ctx->pb, &ptr);
00453         av_free(ptr);
00454     }
00455     avformat_free_context(rtp_ctx);
00456 }
00457