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1
/*
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 * MOV, 3GP, MP4 muxer RTP hinting
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 * Copyright (c) 2010 Martin Storsjo
4
 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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#include "avio_internal.h"
27

    
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int ff_mov_init_hinting(AVFormatContext *s, int index, int src_index)
29
{
30
    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;
49

    
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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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}
65

    
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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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}
92

    
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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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}
119

    
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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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}
144

    
145
/**
146
 * 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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}
197

    
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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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225
        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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        }
235

    
236
        if (sample->offset < 10 && sample->size > 20) {
237
            /* No match found from the start of the sample,
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             * try from the middle of the sample instead. */
239
            sample->offset = sample->size/2;
240
        } else {
241
            /* No match for this sample, remove it */
242
            sample_queue_pop(queue);
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        }
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    }
245
    return -1;
246
}
247

    
248
static void output_immediate(const uint8_t *data, int size,
249
                             AVIOContext *out, int *entries)
250
{
251
    while (size > 0) {
252
        int len = size;
253
        if (len > 14)
254
            len = 14;
255
        avio_w8(out, 1); /* immediate constructor */
256
        avio_w8(out, len); /* amount of valid data */
257
        avio_write(out, data, len);
258
        data += len;
259
        size -= len;
260

    
261
        for (; len < 14; len++)
262
            avio_w8(out, 0);
263

    
264
        (*entries)++;
265
    }
266
}
267

    
268
static void output_match(AVIOContext *out, int match_sample,
269
                         int match_offset, int match_len, int *entries)
270
{
271
    avio_w8(out, 2); /* sample constructor */
272
    avio_w8(out, 0); /* track reference */
273
    avio_wb16(out, match_len);
274
    avio_wb32(out, match_sample);
275
    avio_wb32(out, match_offset);
276
    avio_wb16(out, 1); /* bytes per block */
277
    avio_wb16(out, 1); /* samples per block */
278
    (*entries)++;
279
}
280

    
281
static void describe_payload(const uint8_t *data, int size,
282
                             AVIOContext *out, int *entries,
283
                             HintSampleQueue *queue)
284
{
285
    /* Describe the payload using different constructors */
286
    while (size > 0) {
287
        int match_sample, match_offset, match_len, pos;
288
        if (find_sample_match(data, size, queue, &pos, &match_sample,
289
                              &match_offset, &match_len) < 0)
290
            break;
291
        output_immediate(data, pos, out, entries);
292
        data += pos;
293
        size -= pos;
294
        output_match(out, match_sample, match_offset, match_len, entries);
295
        data += match_len;
296
        size -= match_len;
297
    }
298
    output_immediate(data, size, out, entries);
299
}
300

    
301
/**
302
 * Write an RTP hint (that may contain one or more RTP packets)
303
 * for the packets in data. data contains one or more packets with a
304
 * BE32 size header.
305
 *
306
 * @param out buffer where the hints are written
307
 * @param data buffer containing RTP packets
308
 * @param size the size of the data buffer
309
 * @param trk the MOVTrack for the hint track
310
 * @param pts pointer where the timestamp for the written RTP hint is stored
311
 * @return the number of RTP packets in the written hint
312
 */
313
static int write_hint_packets(AVIOContext *out, const uint8_t *data,
314
                              int size, MOVTrack *trk, int64_t *pts)
315
{
316
    int64_t curpos;
317
    int64_t count_pos, entries_pos;
318
    int count = 0, entries;
319

    
320
    count_pos = avio_tell(out);
321
    /* RTPsample header */
322
    avio_wb16(out, 0); /* packet count */
323
    avio_wb16(out, 0); /* reserved */
324

    
325
    while (size > 4) {
326
        uint32_t packet_len = AV_RB32(data);
327
        uint16_t seq;
328
        uint32_t ts;
329

    
330
        data += 4;
331
        size -= 4;
332
        if (packet_len > size || packet_len <= 12)
333
            break;
334
        if (data[1] >= 200 && data[1] <= 204) {
335
            /* RTCP packet, just skip */
336
            data += packet_len;
337
            size -= packet_len;
338
            continue;
339
        }
340

    
341
        if (packet_len > trk->max_packet_size)
342
            trk->max_packet_size = packet_len;
343

    
344
        seq = AV_RB16(&data[2]);
345
        ts = AV_RB32(&data[4]);
346

    
347
        if (trk->prev_rtp_ts == 0)
348
            trk->prev_rtp_ts = ts;
349
        /* Unwrap the 32-bit RTP timestamp that wraps around often
350
         * into a not (as often) wrapping 64-bit timestamp. */
351
        trk->cur_rtp_ts_unwrapped += (int32_t) (ts - trk->prev_rtp_ts);
352
        trk->prev_rtp_ts = ts;
353
        if (*pts == AV_NOPTS_VALUE)
354
            *pts = trk->cur_rtp_ts_unwrapped;
355

    
356
        count++;
357
        /* RTPpacket header */
358
        avio_wb32(out, 0); /* relative_time */
359
        avio_write(out, data, 2); /* RTP header */
360
        avio_wb16(out, seq); /* RTPsequenceseed */
361
        avio_wb16(out, 0); /* reserved + flags */
362
        entries_pos = avio_tell(out);
363
        avio_wb16(out, 0); /* entry count */
364

    
365
        data += 12;
366
        size -= 12;
367
        packet_len -= 12;
368

    
369
        entries = 0;
370
        /* Write one or more constructors describing the payload data */
371
        describe_payload(data, packet_len, out, &entries, &trk->sample_queue);
372
        data += packet_len;
373
        size -= packet_len;
374

    
375
        curpos = avio_tell(out);
376
        avio_seek(out, entries_pos, SEEK_SET);
377
        avio_wb16(out, entries);
378
        avio_seek(out, curpos, SEEK_SET);
379
    }
380

    
381
    curpos = avio_tell(out);
382
    avio_seek(out, count_pos, SEEK_SET);
383
    avio_wb16(out, count);
384
    avio_seek(out, curpos, SEEK_SET);
385
    return count;
386
}
387

    
388
int ff_mov_add_hinted_packet(AVFormatContext *s, AVPacket *pkt,
389
                             int track_index, int sample)
390
{
391
    MOVMuxContext *mov = s->priv_data;
392
    MOVTrack *trk = &mov->tracks[track_index];
393
    AVFormatContext *rtp_ctx = trk->rtp_ctx;
394
    uint8_t *buf = NULL;
395
    int size;
396
    AVIOContext *hintbuf = NULL;
397
    AVPacket hint_pkt;
398
    int ret = 0, count;
399

    
400
    if (!rtp_ctx)
401
        return AVERROR(ENOENT);
402
    if (!rtp_ctx->pb)
403
        return AVERROR(ENOMEM);
404

    
405
    sample_queue_push(&trk->sample_queue, pkt, sample);
406

    
407
    /* Feed the packet to the RTP muxer */
408
    ff_write_chained(rtp_ctx, 0, pkt, s);
409

    
410
    /* Fetch the output from the RTP muxer, open a new output buffer
411
     * for next time. */
412
    size = avio_close_dyn_buf(rtp_ctx->pb, &buf);
413
    if ((ret = ffio_open_dyn_packet_buf(&rtp_ctx->pb,
414
                                       RTP_MAX_PACKET_SIZE)) < 0)
415
        goto done;
416

    
417
    if (size <= 0)
418
        goto done;
419

    
420
    /* Open a buffer for writing the hint */
421
    if ((ret = avio_open_dyn_buf(&hintbuf)) < 0)
422
        goto done;
423
    av_init_packet(&hint_pkt);
424
    count = write_hint_packets(hintbuf, buf, size, trk, &hint_pkt.dts);
425
    av_freep(&buf);
426

    
427
    /* Write the hint data into the hint track */
428
    hint_pkt.size = size = avio_close_dyn_buf(hintbuf, &buf);
429
    hint_pkt.data = buf;
430
    hint_pkt.pts  = hint_pkt.dts;
431
    hint_pkt.stream_index = track_index;
432
    if (pkt->flags & AV_PKT_FLAG_KEY)
433
        hint_pkt.flags |= AV_PKT_FLAG_KEY;
434
    if (count > 0)
435
        ff_mov_write_packet(s, &hint_pkt);
436
done:
437
    av_free(buf);
438
    sample_queue_retain(&trk->sample_queue);
439
    return ret;
440
}
441

    
442
void ff_mov_close_hinting(MOVTrack *track) {
443
    AVFormatContext* rtp_ctx = track->rtp_ctx;
444
    uint8_t *ptr;
445

    
446
    av_freep(&track->enc);
447
    sample_queue_free(&track->sample_queue);
448
    if (!rtp_ctx)
449
        return;
450
    if (rtp_ctx->pb) {
451
        av_write_trailer(rtp_ctx);
452
        avio_close_dyn_buf(rtp_ctx->pb, &ptr);
453
        av_free(ptr);
454
    }
455
    avformat_free_context(rtp_ctx);
456
}
457