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 
00025 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
00026 {
00027     MOVMuxContext *mov  = s->priv_data;
00028     MOVTrack *track     = &mov->tracks[index];
00029     MOVTrack *src_track = &mov->tracks[src_index];
00030     AVStream *src_st    = s->streams[src_index];
00031     int ret = AVERROR(ENOMEM);
00032     AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);
00033 
00034     track->tag = MKTAG('r','t','p',' ');
00035     track->src_track = src_index;
00036 
00037     if (!rtp_format) {
00038         ret = AVERROR(ENOENT);
00039         goto fail;
00040     }
00041 
00042     track->enc = avcodec_alloc_context();
00043     if (!track->enc)
00044         goto fail;
00045     track->enc->codec_type = AVMEDIA_TYPE_DATA;
00046     track->enc->codec_tag  = track->tag;
00047 
00048     track->rtp_ctx = avformat_alloc_context();
00049     if (!track->rtp_ctx)
00050         goto fail;
00051     track->rtp_ctx->oformat = rtp_format;
00052     if (!av_new_stream(track->rtp_ctx, 0))
00053         goto fail;
00054 
00055     /* Copy stream parameters */
00056     track->rtp_ctx->streams[0]->sample_aspect_ratio =
00057                         src_st->sample_aspect_ratio;
00058 
00059     /* Remove the allocated codec context, link to the original one
00060      * instead, to give the rtp muxer access to codec parameters. */
00061     av_free(track->rtp_ctx->streams[0]->codec);
00062     track->rtp_ctx->streams[0]->codec = src_st->codec;
00063 
00064     if ((ret = url_open_dyn_packet_buf(&track->rtp_ctx->pb,
00065                                        RTP_MAX_PACKET_SIZE)) < 0)
00066         goto fail;
00067     ret = av_write_header(track->rtp_ctx);
00068     if (ret)
00069         goto fail;
00070 
00071     /* Copy the RTP AVStream timebase back to the hint AVStream */
00072     track->timescale = track->rtp_ctx->streams[0]->time_base.den;
00073 
00074     /* Mark the hinted track that packets written to it should be
00075      * sent to this track for hinting. */
00076     src_track->hint_track = index;
00077     return 0;
00078 fail:
00079     av_log(s, AV_LOG_WARNING,
00080            "Unable to initialize hinting of stream %d\n", src_index);
00081     if (track->rtp_ctx && track->rtp_ctx->pb) {
00082         uint8_t *buf;
00083         url_close_dyn_buf(track->rtp_ctx->pb, &buf);
00084         av_free(buf);
00085     }
00086     if (track->rtp_ctx && track->rtp_ctx->streams[0]) {
00087         av_metadata_free(&track->rtp_ctx->streams[0]->metadata);
00088         av_free(track->rtp_ctx->streams[0]);
00089     }
00090     if (track->rtp_ctx) {
00091         av_metadata_free(&track->rtp_ctx->metadata);
00092         av_free(track->rtp_ctx->priv_data);
00093         av_freep(&track->rtp_ctx);
00094     }
00095     av_freep(&track->enc);
00096     /* Set a default timescale, to avoid crashes in dump_format */
00097     track->timescale = 90000;
00098     return ret;
00099 }
00100 
00104 static void sample_queue_pop(HintSampleQueue *queue)
00105 {
00106     if (queue->len <= 0)
00107         return;
00108     if (queue->samples[0].own_data)
00109         av_free(queue->samples[0].data);
00110     queue->len--;
00111     memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
00112 }
00113 
00117 static void sample_queue_free(HintSampleQueue *queue)
00118 {
00119     int i;
00120     for (i = 0; i < queue->len; i++)
00121         if (queue->samples[i].own_data)
00122             av_free(queue->samples[i].data);
00123     av_freep(&queue->samples);
00124     queue->len = 0;
00125     queue->size = 0;
00126 }
00127 
00133 static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
00134 {
00135     /* No need to keep track of smaller samples, since describing them
00136      * with immediates is more efficient. */
00137     if (pkt->size <= 14)
00138         return;
00139     if (!queue->samples || queue->len >= queue->size) {
00140         HintSample* samples;
00141         queue->size += 10;
00142         samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
00143         if (!samples)
00144             return;
00145         queue->samples = samples;
00146     }
00147     queue->samples[queue->len].data = pkt->data;
00148     queue->samples[queue->len].size = pkt->size;
00149     queue->samples[queue->len].sample_number = sample;
00150     queue->samples[queue->len].offset = 0;
00151     queue->samples[queue->len].own_data = 0;
00152     queue->len++;
00153 }
00154 
00158 static void sample_queue_retain(HintSampleQueue *queue)
00159 {
00160     int i;
00161     for (i = 0; i < queue->len; ) {
00162         HintSample *sample = &queue->samples[i];
00163         if (!sample->own_data) {
00164             uint8_t* ptr = av_malloc(sample->size);
00165             if (!ptr) {
00166                 /* Unable to allocate memory for this one, remove it */
00167                 memmove(queue->samples + i, queue->samples + i + 1,
00168                         sizeof(HintSample)*(queue->len - i - 1));
00169                 queue->len--;
00170                 continue;
00171             }
00172             memcpy(ptr, sample->data, sample->size);
00173             sample->data = ptr;
00174             sample->own_data = 1;
00175         }
00176         i++;
00177     }
00178 }
00179 
00196 static int match_segments(const uint8_t *haystack, int h_len,
00197                           const uint8_t *needle, int n_pos, int n_len,
00198                           int *match_h_offset_ptr, int *match_n_offset_ptr,
00199                           int *match_len_ptr)
00200 {
00201     int h_pos;
00202     for (h_pos = 0; h_pos < h_len; h_pos++) {
00203         int match_len = 0;
00204         int match_h_pos, match_n_pos;
00205 
00206         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
00207         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
00208                needle[n_pos + match_len] == haystack[h_pos + match_len])
00209             match_len++;
00210         if (match_len <= 8)
00211             continue;
00212 
00213         /* If a sufficiently large match was found, try to expand
00214          * the matched segment backwards. */
00215         match_h_pos = h_pos;
00216         match_n_pos = n_pos;
00217         while (match_n_pos > 0 && match_h_pos > 0 &&
00218                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
00219             match_n_pos--;
00220             match_h_pos--;
00221             match_len++;
00222         }
00223         if (match_len <= 14)
00224             continue;
00225         *match_h_offset_ptr = match_h_pos;
00226         *match_n_offset_ptr = match_n_pos;
00227         *match_len_ptr = match_len;
00228         return 0;
00229     }
00230     return -1;
00231 }
00232 
00248 static int find_sample_match(const uint8_t *data, int len,
00249                              HintSampleQueue *queue, int *pos,
00250                              int *match_sample, int *match_offset,
00251                              int *match_len)
00252 {
00253     while (queue->len > 0) {
00254         HintSample *sample = &queue->samples[0];
00255         /* If looking for matches in a new sample, skip the first 5 bytes,
00256          * since they often may be modified/removed in the output packet. */
00257         if (sample->offset == 0 && sample->size > 5)
00258             sample->offset = 5;
00259 
00260         if (match_segments(data, len, sample->data, sample->offset,
00261                            sample->size, pos, match_offset, match_len) == 0) {
00262             *match_sample = sample->sample_number;
00263             /* Next time, look for matches at this offset, with a little
00264              * margin to this match. */
00265             sample->offset = *match_offset + *match_len + 5;
00266             if (sample->offset + 10 >= sample->size)
00267                 sample_queue_pop(queue); /* Not enough useful data left */
00268             return 0;
00269         }
00270 
00271         if (sample->offset < 10 && sample->size > 20) {
00272             /* No match found from the start of the sample,
00273              * try from the middle of the sample instead. */
00274             sample->offset = sample->size/2;
00275         } else {
00276             /* No match for this sample, remove it */
00277             sample_queue_pop(queue);
00278         }
00279     }
00280     return -1;
00281 }
00282 
00283 static void output_immediate(const uint8_t *data, int size,
00284                              ByteIOContext *out, int *entries)
00285 {
00286     while (size > 0) {
00287         int len = size;
00288         if (len > 14)
00289             len = 14;
00290         put_byte(out, 1); /* immediate constructor */
00291         put_byte(out, len); /* amount of valid data */
00292         put_buffer(out, data, len);
00293         data += len;
00294         size -= len;
00295 
00296         for (; len < 14; len++)
00297             put_byte(out, 0);
00298 
00299         (*entries)++;
00300     }
00301 }
00302 
00303 static void output_match(ByteIOContext *out, int match_sample,
00304                          int match_offset, int match_len, int *entries)
00305 {
00306     put_byte(out, 2); /* sample constructor */
00307     put_byte(out, 0); /* track reference */
00308     put_be16(out, match_len);
00309     put_be32(out, match_sample);
00310     put_be32(out, match_offset);
00311     put_be16(out, 1); /* bytes per block */
00312     put_be16(out, 1); /* samples per block */
00313     (*entries)++;
00314 }
00315 
00316 static void describe_payload(const uint8_t *data, int size,
00317                              ByteIOContext *out, int *entries,
00318                              HintSampleQueue *queue)
00319 {
00320     /* Describe the payload using different constructors */
00321     while (size > 0) {
00322         int match_sample, match_offset, match_len, pos;
00323         if (find_sample_match(data, size, queue, &pos, &match_sample,
00324                               &match_offset, &match_len) < 0)
00325             break;
00326         output_immediate(data, pos, out, entries);
00327         data += pos;
00328         size -= pos;
00329         output_match(out, match_sample, match_offset, match_len, entries);
00330         data += match_len;
00331         size -= match_len;
00332     }
00333     output_immediate(data, size, out, entries);
00334 }
00335 
00348 static int write_hint_packets(ByteIOContext *out, const uint8_t *data,
00349                               int size, MOVTrack *trk, int64_t *pts)
00350 {
00351     int64_t curpos;
00352     int64_t count_pos, entries_pos;
00353     int count = 0, entries;
00354 
00355     count_pos = url_ftell(out);
00356     /* RTPsample header */
00357     put_be16(out, 0); /* packet count */
00358     put_be16(out, 0); /* reserved */
00359 
00360     while (size > 4) {
00361         uint32_t packet_len = AV_RB32(data);
00362         uint16_t seq;
00363         uint32_t ts;
00364 
00365         data += 4;
00366         size -= 4;
00367         if (packet_len > size || packet_len <= 12)
00368             break;
00369         if (data[1] >= 200 && data[1] <= 204) {
00370             /* RTCP packet, just skip */
00371             data += packet_len;
00372             size -= packet_len;
00373             continue;
00374         }
00375 
00376         if (packet_len > trk->max_packet_size)
00377             trk->max_packet_size = packet_len;
00378 
00379         seq = AV_RB16(&data[2]);
00380         ts = AV_RB32(&data[4]);
00381 
00382         if (trk->prev_rtp_ts == 0)
00383             trk->prev_rtp_ts = ts;
00384         /* Unwrap the 32-bit RTP timestamp that wraps around often
00385          * into a not (as often) wrapping 64-bit timestamp. */
00386         trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
00387         trk->prev_rtp_ts = ts;
00388         if (*pts == AV_NOPTS_VALUE)
00389             *pts = trk->cur_rtp_ts_unwrapped;
00390 
00391         count++;
00392         /* RTPpacket header */
00393         put_be32(out, 0); /* relative_time */
00394         put_buffer(out, data, 2); /* RTP header */
00395         put_be16(out, seq); /* RTPsequenceseed */
00396         put_be16(out, 0); /* reserved + flags */
00397         entries_pos = url_ftell(out);
00398         put_be16(out, 0); /* entry count */
00399 
00400         data += 12;
00401         size -= 12;
00402         packet_len -= 12;
00403 
00404         entries = 0;
00405         /* Write one or more constructors describing the payload data */
00406         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
00407         data += packet_len;
00408         size -= packet_len;
00409 
00410         curpos = url_ftell(out);
00411         url_fseek(out, entries_pos, SEEK_SET);
00412         put_be16(out, entries);
00413         url_fseek(out, curpos, SEEK_SET);
00414     }
00415 
00416     curpos = url_ftell(out);
00417     url_fseek(out, count_pos, SEEK_SET);
00418     put_be16(out, count);
00419     url_fseek(out, curpos, SEEK_SET);
00420     return count;
00421 }
00422 
00423 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
00424                              int track_index, int sample)
00425 {
00426     MOVMuxContext *mov = s->priv_data;
00427     MOVTrack *trk = &mov->tracks[track_index];
00428     AVFormatContext *rtp_ctx = trk->rtp_ctx;
00429     uint8_t *buf = NULL;
00430     int size;
00431     ByteIOContext *hintbuf = NULL;
00432     AVPacket hint_pkt;
00433     AVPacket local_pkt;
00434     int ret = 0, count;
00435 
00436     if (!rtp_ctx)
00437         return AVERROR(ENOENT);
00438     if (!rtp_ctx->pb)
00439         return AVERROR(ENOMEM);
00440 
00441     sample_queue_push(&trk->sample_queue, pkt, sample);
00442 
00443     /* Feed the packet to the RTP muxer */
00444     local_pkt = *pkt;
00445     local_pkt.stream_index = 0;
00446     local_pkt.pts = av_rescale_q(pkt->pts,
00447         s->streams[pkt->stream_index]->time_base,
00448         rtp_ctx->streams[0]->time_base);
00449     local_pkt.dts = av_rescale_q(pkt->dts,
00450         s->streams[pkt->stream_index]->time_base,
00451         rtp_ctx->streams[0]->time_base);
00452     av_write_frame(rtp_ctx, &local_pkt);
00453 
00454     /* Fetch the output from the RTP muxer, open a new output buffer
00455      * for next time. */
00456     size = url_close_dyn_buf(rtp_ctx->pb, &buf);
00457     if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,
00458                                        RTP_MAX_PACKET_SIZE)) < 0)
00459         goto done;
00460 
00461     if (size <= 0)
00462         goto done;
00463 
00464     /* Open a buffer for writing the hint */
00465     if ((ret = url_open_dyn_buf(&hintbuf)) < 0)
00466         goto done;
00467     av_init_packet(&hint_pkt);
00468     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
00469     av_freep(&buf);
00470 
00471     /* Write the hint data into the hint track */
00472     hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);
00473     hint_pkt.data = buf;
00474     hint_pkt.pts  = hint_pkt.dts;
00475     hint_pkt.stream_index = track_index;
00476     if (pkt->flags & AV_PKT_FLAG_KEY)
00477         hint_pkt.flags |= AV_PKT_FLAG_KEY;
00478     if (count > 0)
00479         ff_mov_write_packet(s, &hint_pkt);
00480 done:
00481     av_free(buf);
00482     sample_queue_retain(&trk->sample_queue);
00483     return ret;
00484 }
00485 
00486 void ff_mov_close_hinting(MOVTrack *track) {
00487     AVFormatContext* rtp_ctx = track->rtp_ctx;
00488     uint8_t *ptr;
00489 
00490     av_freep(&track->enc);
00491     sample_queue_free(&track->sample_queue);
00492     if (!rtp_ctx)
00493         return;
00494     if (rtp_ctx->pb) {
00495         av_write_trailer(rtp_ctx);
00496         url_close_dyn_buf(rtp_ctx->pb, &ptr);
00497         av_free(ptr);
00498     }
00499     av_metadata_free(&rtp_ctx->streams[0]->metadata);
00500     av_metadata_free(&rtp_ctx->metadata);
00501     av_free(rtp_ctx->streams[0]);
00502     av_freep(&rtp_ctx);
00503 }
00504