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 
00026 int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
00027 {
00028     MOVMuxContext *mov  = s->priv_data;
00029     MOVTrack *track     = &mov->tracks[index];
00030     MOVTrack *src_track = &mov->tracks[src_index];
00031     AVStream *src_st    = s->streams[src_index];
00032     int ret = AVERROR(ENOMEM);
00033     AVOutputFormat *rtp_format = av_guess_format("rtp", NULL, NULL);
00034 
00035     track->tag = MKTAG('r','t','p',' ');
00036     track->src_track = src_index;
00037 
00038     if (!rtp_format) {
00039         ret = AVERROR(ENOENT);
00040         goto fail;
00041     }
00042 
00043     track->enc = avcodec_alloc_context();
00044     if (!track->enc)
00045         goto fail;
00046     track->enc->codec_type = AVMEDIA_TYPE_DATA;
00047     track->enc->codec_tag  = track->tag;
00048 
00049     track->rtp_ctx = avformat_alloc_context();
00050     if (!track->rtp_ctx)
00051         goto fail;
00052     track->rtp_ctx->oformat = rtp_format;
00053     if (!av_new_stream(track->rtp_ctx, 0))
00054         goto fail;
00055 
00056     /* Copy stream parameters */
00057     track->rtp_ctx->streams[0]->sample_aspect_ratio =
00058                         src_st->sample_aspect_ratio;
00059 
00060     /* Remove the allocated codec context, link to the original one
00061      * instead, to give the rtp muxer access to codec parameters. */
00062     av_free(track->rtp_ctx->streams[0]->codec);
00063     track->rtp_ctx->streams[0]->codec = src_st->codec;
00064 
00065     if ((ret = url_open_dyn_packet_buf(&track->rtp_ctx->pb,
00066                                        RTP_MAX_PACKET_SIZE)) < 0)
00067         goto fail;
00068     ret = av_write_header(track->rtp_ctx);
00069     if (ret)
00070         goto fail;
00071 
00072     /* Copy the RTP AVStream timebase back to the hint AVStream */
00073     track->timescale = track->rtp_ctx->streams[0]->time_base.den;
00074 
00075     /* Mark the hinted track that packets written to it should be
00076      * sent to this track for hinting. */
00077     src_track->hint_track = index;
00078     return 0;
00079 fail:
00080     av_log(s, AV_LOG_WARNING,
00081            "Unable to initialize hinting of stream %d\n", src_index);
00082     if (track->rtp_ctx && track->rtp_ctx->pb) {
00083         uint8_t *buf;
00084         url_close_dyn_buf(track->rtp_ctx->pb, &buf);
00085         av_free(buf);
00086     }
00087     if (track->rtp_ctx && track->rtp_ctx->streams[0]) {
00088         av_metadata_free(&track->rtp_ctx->streams[0]->metadata);
00089         av_free(track->rtp_ctx->streams[0]);
00090     }
00091     if (track->rtp_ctx) {
00092         av_metadata_free(&track->rtp_ctx->metadata);
00093         av_free(track->rtp_ctx->priv_data);
00094         av_freep(&track->rtp_ctx);
00095     }
00096     av_freep(&track->enc);
00097     /* Set a default timescale, to avoid crashes in dump_format */
00098     track->timescale = 90000;
00099     return ret;
00100 }
00101 
00105 static void sample_queue_pop(HintSampleQueue *queue)
00106 {
00107     if (queue->len <= 0)
00108         return;
00109     if (queue->samples[0].own_data)
00110         av_free(queue->samples[0].data);
00111     queue->len--;
00112     memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
00113 }
00114 
00118 static void sample_queue_free(HintSampleQueue *queue)
00119 {
00120     int i;
00121     for (i = 0; i < queue->len; i++)
00122         if (queue->samples[i].own_data)
00123             av_free(queue->samples[i].data);
00124     av_freep(&queue->samples);
00125     queue->len = 0;
00126     queue->size = 0;
00127 }
00128 
00134 static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
00135 {
00136     /* No need to keep track of smaller samples, since describing them
00137      * with immediates is more efficient. */
00138     if (pkt->size <= 14)
00139         return;
00140     if (!queue->samples || queue->len >= queue->size) {
00141         HintSample* samples;
00142         queue->size += 10;
00143         samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
00144         if (!samples)
00145             return;
00146         queue->samples = samples;
00147     }
00148     queue->samples[queue->len].data = pkt->data;
00149     queue->samples[queue->len].size = pkt->size;
00150     queue->samples[queue->len].sample_number = sample;
00151     queue->samples[queue->len].offset = 0;
00152     queue->samples[queue->len].own_data = 0;
00153     queue->len++;
00154 }
00155 
00159 static void sample_queue_retain(HintSampleQueue *queue)
00160 {
00161     int i;
00162     for (i = 0; i < queue->len; ) {
00163         HintSample *sample = &queue->samples[i];
00164         if (!sample->own_data) {
00165             uint8_t* ptr = av_malloc(sample->size);
00166             if (!ptr) {
00167                 /* Unable to allocate memory for this one, remove it */
00168                 memmove(queue->samples + i, queue->samples + i + 1,
00169                         sizeof(HintSample)*(queue->len - i - 1));
00170                 queue->len--;
00171                 continue;
00172             }
00173             memcpy(ptr, sample->data, sample->size);
00174             sample->data = ptr;
00175             sample->own_data = 1;
00176         }
00177         i++;
00178     }
00179 }
00180 
00197 static int match_segments(const uint8_t *haystack, int h_len,
00198                           const uint8_t *needle, int n_pos, int n_len,
00199                           int *match_h_offset_ptr, int *match_n_offset_ptr,
00200                           int *match_len_ptr)
00201 {
00202     int h_pos;
00203     for (h_pos = 0; h_pos < h_len; h_pos++) {
00204         int match_len = 0;
00205         int match_h_pos, match_n_pos;
00206 
00207         /* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
00208         while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
00209                needle[n_pos + match_len] == haystack[h_pos + match_len])
00210             match_len++;
00211         if (match_len <= 8)
00212             continue;
00213 
00214         /* If a sufficiently large match was found, try to expand
00215          * the matched segment backwards. */
00216         match_h_pos = h_pos;
00217         match_n_pos = n_pos;
00218         while (match_n_pos > 0 && match_h_pos > 0 &&
00219                needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
00220             match_n_pos--;
00221             match_h_pos--;
00222             match_len++;
00223         }
00224         if (match_len <= 14)
00225             continue;
00226         *match_h_offset_ptr = match_h_pos;
00227         *match_n_offset_ptr = match_n_pos;
00228         *match_len_ptr = match_len;
00229         return 0;
00230     }
00231     return -1;
00232 }
00233 
00249 static int find_sample_match(const uint8_t *data, int len,
00250                              HintSampleQueue *queue, int *pos,
00251                              int *match_sample, int *match_offset,
00252                              int *match_len)
00253 {
00254     while (queue->len > 0) {
00255         HintSample *sample = &queue->samples[0];
00256         /* If looking for matches in a new sample, skip the first 5 bytes,
00257          * since they often may be modified/removed in the output packet. */
00258         if (sample->offset == 0 && sample->size > 5)
00259             sample->offset = 5;
00260 
00261         if (match_segments(data, len, sample->data, sample->offset,
00262                            sample->size, pos, match_offset, match_len) == 0) {
00263             *match_sample = sample->sample_number;
00264             /* Next time, look for matches at this offset, with a little
00265              * margin to this match. */
00266             sample->offset = *match_offset + *match_len + 5;
00267             if (sample->offset + 10 >= sample->size)
00268                 sample_queue_pop(queue); /* Not enough useful data left */
00269             return 0;
00270         }
00271 
00272         if (sample->offset < 10 && sample->size > 20) {
00273             /* No match found from the start of the sample,
00274              * try from the middle of the sample instead. */
00275             sample->offset = sample->size/2;
00276         } else {
00277             /* No match for this sample, remove it */
00278             sample_queue_pop(queue);
00279         }
00280     }
00281     return -1;
00282 }
00283 
00284 static void output_immediate(const uint8_t *data, int size,
00285                              ByteIOContext *out, int *entries)
00286 {
00287     while (size > 0) {
00288         int len = size;
00289         if (len > 14)
00290             len = 14;
00291         put_byte(out, 1); /* immediate constructor */
00292         put_byte(out, len); /* amount of valid data */
00293         put_buffer(out, data, len);
00294         data += len;
00295         size -= len;
00296 
00297         for (; len < 14; len++)
00298             put_byte(out, 0);
00299 
00300         (*entries)++;
00301     }
00302 }
00303 
00304 static void output_match(ByteIOContext *out, int match_sample,
00305                          int match_offset, int match_len, int *entries)
00306 {
00307     put_byte(out, 2); /* sample constructor */
00308     put_byte(out, 0); /* track reference */
00309     put_be16(out, match_len);
00310     put_be32(out, match_sample);
00311     put_be32(out, match_offset);
00312     put_be16(out, 1); /* bytes per block */
00313     put_be16(out, 1); /* samples per block */
00314     (*entries)++;
00315 }
00316 
00317 static void describe_payload(const uint8_t *data, int size,
00318                              ByteIOContext *out, int *entries,
00319                              HintSampleQueue *queue)
00320 {
00321     /* Describe the payload using different constructors */
00322     while (size > 0) {
00323         int match_sample, match_offset, match_len, pos;
00324         if (find_sample_match(data, size, queue, &pos, &match_sample,
00325                               &match_offset, &match_len) < 0)
00326             break;
00327         output_immediate(data, pos, out, entries);
00328         data += pos;
00329         size -= pos;
00330         output_match(out, match_sample, match_offset, match_len, entries);
00331         data += match_len;
00332         size -= match_len;
00333     }
00334     output_immediate(data, size, out, entries);
00335 }
00336 
00349 static int write_hint_packets(ByteIOContext *out, const uint8_t *data,
00350                               int size, MOVTrack *trk, int64_t *pts)
00351 {
00352     int64_t curpos;
00353     int64_t count_pos, entries_pos;
00354     int count = 0, entries;
00355 
00356     count_pos = url_ftell(out);
00357     /* RTPsample header */
00358     put_be16(out, 0); /* packet count */
00359     put_be16(out, 0); /* reserved */
00360 
00361     while (size > 4) {
00362         uint32_t packet_len = AV_RB32(data);
00363         uint16_t seq;
00364         uint32_t ts;
00365 
00366         data += 4;
00367         size -= 4;
00368         if (packet_len > size || packet_len <= 12)
00369             break;
00370         if (data[1] >= 200 && data[1] <= 204) {
00371             /* RTCP packet, just skip */
00372             data += packet_len;
00373             size -= packet_len;
00374             continue;
00375         }
00376 
00377         if (packet_len > trk->max_packet_size)
00378             trk->max_packet_size = packet_len;
00379 
00380         seq = AV_RB16(&data[2]);
00381         ts = AV_RB32(&data[4]);
00382 
00383         if (trk->prev_rtp_ts == 0)
00384             trk->prev_rtp_ts = ts;
00385         /* Unwrap the 32-bit RTP timestamp that wraps around often
00386          * into a not (as often) wrapping 64-bit timestamp. */
00387         trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
00388         trk->prev_rtp_ts = ts;
00389         if (*pts == AV_NOPTS_VALUE)
00390             *pts = trk->cur_rtp_ts_unwrapped;
00391 
00392         count++;
00393         /* RTPpacket header */
00394         put_be32(out, 0); /* relative_time */
00395         put_buffer(out, data, 2); /* RTP header */
00396         put_be16(out, seq); /* RTPsequenceseed */
00397         put_be16(out, 0); /* reserved + flags */
00398         entries_pos = url_ftell(out);
00399         put_be16(out, 0); /* entry count */
00400 
00401         data += 12;
00402         size -= 12;
00403         packet_len -= 12;
00404 
00405         entries = 0;
00406         /* Write one or more constructors describing the payload data */
00407         describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
00408         data += packet_len;
00409         size -= packet_len;
00410 
00411         curpos = url_ftell(out);
00412         url_fseek(out, entries_pos, SEEK_SET);
00413         put_be16(out, entries);
00414         url_fseek(out, curpos, SEEK_SET);
00415     }
00416 
00417     curpos = url_ftell(out);
00418     url_fseek(out, count_pos, SEEK_SET);
00419     put_be16(out, count);
00420     url_fseek(out, curpos, SEEK_SET);
00421     return count;
00422 }
00423 
00424 int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
00425                              int track_index, int sample)
00426 {
00427     MOVMuxContext *mov = s->priv_data;
00428     MOVTrack *trk = &mov->tracks[track_index];
00429     AVFormatContext *rtp_ctx = trk->rtp_ctx;
00430     uint8_t *buf = NULL;
00431     int size;
00432     ByteIOContext *hintbuf = NULL;
00433     AVPacket hint_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     ff_write_chained(rtp_ctx, 0, pkt, s);
00445 
00446     /* Fetch the output from the RTP muxer, open a new output buffer
00447      * for next time. */
00448     size = url_close_dyn_buf(rtp_ctx->pb, &buf);
00449     if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,
00450                                        RTP_MAX_PACKET_SIZE)) < 0)
00451         goto done;
00452 
00453     if (size <= 0)
00454         goto done;
00455 
00456     /* Open a buffer for writing the hint */
00457     if ((ret = url_open_dyn_buf(&hintbuf)) < 0)
00458         goto done;
00459     av_init_packet(&hint_pkt);
00460     count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
00461     av_freep(&buf);
00462 
00463     /* Write the hint data into the hint track */
00464     hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);
00465     hint_pkt.data = buf;
00466     hint_pkt.pts  = hint_pkt.dts;
00467     hint_pkt.stream_index = track_index;
00468     if (pkt->flags & AV_PKT_FLAG_KEY)
00469         hint_pkt.flags |= AV_PKT_FLAG_KEY;
00470     if (count > 0)
00471         ff_mov_write_packet(s, &hint_pkt);
00472 done:
00473     av_free(buf);
00474     sample_queue_retain(&trk->sample_queue);
00475     return ret;
00476 }
00477 
00478 void ff_mov_close_hinting(MOVTrack *track) {
00479     AVFormatContext* rtp_ctx = track->rtp_ctx;
00480     uint8_t *ptr;
00481 
00482     av_freep(&track->enc);
00483     sample_queue_free(&track->sample_queue);
00484     if (!rtp_ctx)
00485         return;
00486     if (rtp_ctx->pb) {
00487         av_write_trailer(rtp_ctx);
00488         url_close_dyn_buf(rtp_ctx->pb, &ptr);
00489         av_free(ptr);
00490     }
00491     av_metadata_free(&rtp_ctx->streams[0]->metadata);
00492     av_metadata_free(&rtp_ctx->metadata);
00493     av_free(rtp_ctx->streams[0]);
00494     av_freep(&rtp_ctx);
00495 }
00496