457 lines
15 KiB
C
457 lines
15 KiB
C
/*
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* MOV, 3GP, MP4 muxer RTP hinting
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* Copyright (c) 2010 Martin Storsjo
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "movenc.h"
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#include "libavutil/intreadwrite.h"
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#include "internal.h"
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#include "rtpenc_chain.h"
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int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
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{
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MOVMuxContext *mov = s->priv_data;
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MOVTrack *track = &mov->tracks[index];
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MOVTrack *src_track = &mov->tracks[src_index];
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AVStream *src_st = s->streams[src_index];
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int ret = AVERROR(ENOMEM);
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track->tag = MKTAG('r','t','p',' ');
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track->src_track = src_index;
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track->enc = avcodec_alloc_context();
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if (!track->enc)
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goto fail;
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track->enc->codec_type = AVMEDIA_TYPE_DATA;
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track->enc->codec_tag = track->tag;
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track->rtp_ctx = ff_rtp_chain_mux_open(s, src_st, NULL,
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RTP_MAX_PACKET_SIZE);
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if (!track->rtp_ctx)
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goto fail;
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/* Copy the RTP AVStream timebase back to the hint AVStream */
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track->timescale = track->rtp_ctx->streams[0]->time_base.den;
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/* Mark the hinted track that packets written to it should be
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* sent to this track for hinting. */
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src_track->hint_track = index;
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return 0;
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fail:
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av_log(s, AV_LOG_WARNING,
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"Unable to initialize hinting of stream %d\n", src_index);
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av_freep(&track->enc);
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/* Set a default timescale, to avoid crashes in av_dump_format */
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track->timescale = 90000;
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return ret;
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}
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/**
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* Remove the first sample from the sample queue.
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*/
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static void sample_queue_pop(HintSampleQueue *queue)
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{
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if (queue->len <= 0)
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return;
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if (queue->samples[0].own_data)
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av_free(queue->samples[0].data);
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queue->len--;
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memmove(queue->samples, queue->samples + 1, sizeof(HintSample)*queue->len);
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}
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/**
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* Empty the sample queue, releasing all memory.
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*/
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static void sample_queue_free(HintSampleQueue *queue)
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{
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int i;
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for (i = 0; i < queue->len; i++)
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if (queue->samples[i].own_data)
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av_free(queue->samples[i].data);
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av_freep(&queue->samples);
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queue->len = 0;
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queue->size = 0;
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}
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/**
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* Add a reference to the sample data to the sample queue. The data is
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* not copied. sample_queue_retain should be called before pkt->data
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* is reused/freed.
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*/
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static void sample_queue_push(HintSampleQueue *queue, AVPacket *pkt, int sample)
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{
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/* No need to keep track of smaller samples, since describing them
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* with immediates is more efficient. */
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if (pkt->size <= 14)
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return;
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if (!queue->samples || queue->len >= queue->size) {
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HintSample* samples;
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queue->size += 10;
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samples = av_realloc(queue->samples, sizeof(HintSample)*queue->size);
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if (!samples)
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return;
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queue->samples = samples;
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}
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queue->samples[queue->len].data = pkt->data;
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queue->samples[queue->len].size = pkt->size;
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queue->samples[queue->len].sample_number = sample;
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queue->samples[queue->len].offset = 0;
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queue->samples[queue->len].own_data = 0;
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queue->len++;
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}
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/**
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* Make local copies of all referenced sample data in the queue.
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*/
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static void sample_queue_retain(HintSampleQueue *queue)
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{
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int i;
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for (i = 0; i < queue->len; ) {
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HintSample *sample = &queue->samples[i];
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if (!sample->own_data) {
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uint8_t* ptr = av_malloc(sample->size);
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if (!ptr) {
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/* Unable to allocate memory for this one, remove it */
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memmove(queue->samples + i, queue->samples + i + 1,
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sizeof(HintSample)*(queue->len - i - 1));
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queue->len--;
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continue;
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}
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memcpy(ptr, sample->data, sample->size);
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sample->data = ptr;
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sample->own_data = 1;
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}
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i++;
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}
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}
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/**
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* Find matches of needle[n_pos ->] within haystack. If a sufficiently
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* large match is found, matching bytes before n_pos are included
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* in the match, too (within the limits of the arrays).
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*
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* @param haystack buffer that may contain parts of needle
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* @param h_len length of the haystack buffer
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* @param needle buffer containing source data that have been used to
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* construct haystack
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* @param n_pos start position in needle used for looking for matches
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* @param n_len length of the needle buffer
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* @param match_h_offset_ptr offset of the first matching byte within haystack
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* @param match_n_offset_ptr offset of the first matching byte within needle
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* @param match_len_ptr length of the matched segment
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* @return 0 if a match was found, < 0 if no match was found
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*/
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static int match_segments(const uint8_t *haystack, int h_len,
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const uint8_t *needle, int n_pos, int n_len,
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int *match_h_offset_ptr, int *match_n_offset_ptr,
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int *match_len_ptr)
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{
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int h_pos;
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for (h_pos = 0; h_pos < h_len; h_pos++) {
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int match_len = 0;
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int match_h_pos, match_n_pos;
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/* Check how many bytes match at needle[n_pos] and haystack[h_pos] */
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while (h_pos + match_len < h_len && n_pos + match_len < n_len &&
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needle[n_pos + match_len] == haystack[h_pos + match_len])
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match_len++;
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if (match_len <= 8)
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continue;
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/* If a sufficiently large match was found, try to expand
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* the matched segment backwards. */
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match_h_pos = h_pos;
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match_n_pos = n_pos;
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while (match_n_pos > 0 && match_h_pos > 0 &&
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needle[match_n_pos - 1] == haystack[match_h_pos - 1]) {
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match_n_pos--;
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match_h_pos--;
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match_len++;
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}
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if (match_len <= 14)
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continue;
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*match_h_offset_ptr = match_h_pos;
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*match_n_offset_ptr = match_n_pos;
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*match_len_ptr = match_len;
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return 0;
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}
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return -1;
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}
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/**
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* Look for segments in samples in the sample queue matching the data
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* in ptr. Samples not matching are removed from the queue. If a match
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* is found, the next time it will look for matches starting from the
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* end of the previous matched segment.
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*
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* @param data data to find matches for in the sample queue
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* @param len length of the data buffer
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* @param queue samples used for looking for matching segments
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* @param pos the offset in data of the matched segment
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* @param match_sample the number of the sample that contained the match
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* @param match_offset the offset of the matched segment within the sample
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* @param match_len the length of the matched segment
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* @return 0 if a match was found, < 0 if no match was found
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*/
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static int find_sample_match(const uint8_t *data, int len,
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HintSampleQueue *queue, int *pos,
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int *match_sample, int *match_offset,
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int *match_len)
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{
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while (queue->len > 0) {
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HintSample *sample = &queue->samples[0];
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/* If looking for matches in a new sample, skip the first 5 bytes,
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* since they often may be modified/removed in the output packet. */
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if (sample->offset == 0 && sample->size > 5)
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sample->offset = 5;
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if (match_segments(data, len, sample->data, sample->offset,
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sample->size, pos, match_offset, match_len) == 0) {
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*match_sample = sample->sample_number;
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/* Next time, look for matches at this offset, with a little
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* margin to this match. */
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sample->offset = *match_offset + *match_len + 5;
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if (sample->offset + 10 >= sample->size)
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sample_queue_pop(queue); /* Not enough useful data left */
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return 0;
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}
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if (sample->offset < 10 && sample->size > 20) {
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/* No match found from the start of the sample,
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* try from the middle of the sample instead. */
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sample->offset = sample->size/2;
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} else {
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/* No match for this sample, remove it */
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sample_queue_pop(queue);
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}
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}
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return -1;
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}
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static void output_immediate(const uint8_t *data, int size,
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AVIOContext *out, int *entries)
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{
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while (size > 0) {
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int len = size;
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if (len > 14)
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len = 14;
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avio_w8(out, 1); /* immediate constructor */
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avio_w8(out, len); /* amount of valid data */
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avio_write(out, data, len);
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data += len;
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size -= len;
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for (; len < 14; len++)
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avio_w8(out, 0);
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(*entries)++;
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}
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}
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static void output_match(AVIOContext *out, int match_sample,
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int match_offset, int match_len, int *entries)
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{
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avio_w8(out, 2); /* sample constructor */
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avio_w8(out, 0); /* track reference */
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avio_wb16(out, match_len);
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avio_wb32(out, match_sample);
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avio_wb32(out, match_offset);
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avio_wb16(out, 1); /* bytes per block */
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avio_wb16(out, 1); /* samples per block */
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(*entries)++;
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}
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static void describe_payload(const uint8_t *data, int size,
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AVIOContext *out, int *entries,
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HintSampleQueue *queue)
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{
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/* Describe the payload using different constructors */
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while (size > 0) {
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int match_sample, match_offset, match_len, pos;
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if (find_sample_match(data, size, queue, &pos, &match_sample,
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&match_offset, &match_len) < 0)
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break;
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output_immediate(data, pos, out, entries);
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data += pos;
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size -= pos;
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output_match(out, match_sample, match_offset, match_len, entries);
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data += match_len;
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size -= match_len;
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}
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output_immediate(data, size, out, entries);
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}
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/**
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* Write an RTP hint (that may contain one or more RTP packets)
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* for the packets in data. data contains one or more packets with a
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* BE32 size header.
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*
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* @param out buffer where the hints are written
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* @param data buffer containing RTP packets
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* @param size the size of the data buffer
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* @param trk the MOVTrack for the hint track
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* @param pts pointer where the timestamp for the written RTP hint is stored
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* @return the number of RTP packets in the written hint
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*/
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static int write_hint_packets(AVIOContext *out, const uint8_t *data,
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int size, MOVTrack *trk, int64_t *pts)
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{
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int64_t curpos;
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int64_t count_pos, entries_pos;
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int count = 0, entries;
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count_pos = avio_tell(out);
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/* RTPsample header */
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avio_wb16(out, 0); /* packet count */
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avio_wb16(out, 0); /* reserved */
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while (size > 4) {
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uint32_t packet_len = AV_RB32(data);
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uint16_t seq;
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uint32_t ts;
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data += 4;
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size -= 4;
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if (packet_len > size || packet_len <= 12)
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break;
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if (data[1] >= 200 && data[1] <= 204) {
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/* RTCP packet, just skip */
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data += packet_len;
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size -= packet_len;
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continue;
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}
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if (packet_len > trk->max_packet_size)
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trk->max_packet_size = packet_len;
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seq = AV_RB16(&data[2]);
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ts = AV_RB32(&data[4]);
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if (trk->prev_rtp_ts == 0)
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trk->prev_rtp_ts = ts;
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/* Unwrap the 32-bit RTP timestamp that wraps around often
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* into a not (as often) wrapping 64-bit timestamp. */
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trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
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trk->prev_rtp_ts = ts;
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if (*pts == AV_NOPTS_VALUE)
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*pts = trk->cur_rtp_ts_unwrapped;
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count++;
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/* RTPpacket header */
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avio_wb32(out, 0); /* relative_time */
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avio_write(out, data, 2); /* RTP header */
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avio_wb16(out, seq); /* RTPsequenceseed */
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avio_wb16(out, 0); /* reserved + flags */
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entries_pos = avio_tell(out);
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avio_wb16(out, 0); /* entry count */
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data += 12;
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size -= 12;
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packet_len -= 12;
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entries = 0;
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/* Write one or more constructors describing the payload data */
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describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
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data += packet_len;
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size -= packet_len;
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curpos = avio_tell(out);
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avio_seek(out, entries_pos, SEEK_SET);
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avio_wb16(out, entries);
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avio_seek(out, curpos, SEEK_SET);
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}
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curpos = avio_tell(out);
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avio_seek(out, count_pos, SEEK_SET);
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avio_wb16(out, count);
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avio_seek(out, curpos, SEEK_SET);
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return count;
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}
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int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
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int track_index, int sample)
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{
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MOVMuxContext *mov = s->priv_data;
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MOVTrack *trk = &mov->tracks[track_index];
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AVFormatContext *rtp_ctx = trk->rtp_ctx;
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uint8_t *buf = NULL;
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int size;
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AVIOContext *hintbuf = NULL;
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AVPacket hint_pkt;
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int ret = 0, count;
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if (!rtp_ctx)
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return AVERROR(ENOENT);
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if (!rtp_ctx->pb)
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return AVERROR(ENOMEM);
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sample_queue_push(&trk->sample_queue, pkt, sample);
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/* Feed the packet to the RTP muxer */
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ff_write_chained(rtp_ctx, 0, pkt, s);
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/* Fetch the output from the RTP muxer, open a new output buffer
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* for next time. */
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size = url_close_dyn_buf(rtp_ctx->pb, &buf);
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if ((ret = url_open_dyn_packet_buf(&rtp_ctx->pb,
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RTP_MAX_PACKET_SIZE)) < 0)
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goto done;
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if (size <= 0)
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goto done;
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/* Open a buffer for writing the hint */
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if ((ret = url_open_dyn_buf(&hintbuf)) < 0)
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goto done;
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av_init_packet(&hint_pkt);
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count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
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av_freep(&buf);
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/* Write the hint data into the hint track */
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hint_pkt.size = size = url_close_dyn_buf(hintbuf, &buf);
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hint_pkt.data = buf;
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hint_pkt.pts = hint_pkt.dts;
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hint_pkt.stream_index = track_index;
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if (pkt->flags & AV_PKT_FLAG_KEY)
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hint_pkt.flags |= AV_PKT_FLAG_KEY;
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if (count > 0)
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ff_mov_write_packet(s, &hint_pkt);
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done:
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av_free(buf);
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sample_queue_retain(&trk->sample_queue);
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return ret;
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}
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void ff_mov_close_hinting(MOVTrack *track) {
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AVFormatContext* rtp_ctx = track->rtp_ctx;
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uint8_t *ptr;
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av_freep(&track->enc);
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sample_queue_free(&track->sample_queue);
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if (!rtp_ctx)
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return;
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if (rtp_ctx->pb) {
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av_write_trailer(rtp_ctx);
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url_close_dyn_buf(rtp_ctx->pb, &ptr);
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av_free(ptr);
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}
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avformat_free_context(rtp_ctx);
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}
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