mirror of
https://git.ffmpeg.org/ffmpeg.git
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251 lines
8.1 KiB
C
251 lines
8.1 KiB
C
/*
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* MxPEG clip file demuxer
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* Copyright (c) 2010 Anatoly Nenashev
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*
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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 "libavutil/intreadwrite.h"
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#include "libavcodec/mjpeg.h"
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#include "avformat.h"
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#include "internal.h"
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#include "avio.h"
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#define DEFAULT_PACKET_SIZE 1024
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#define OVERREAD_SIZE 3
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typedef struct MXGContext {
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uint8_t *buffer;
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uint8_t *buffer_ptr;
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uint8_t *soi_ptr;
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unsigned int buffer_size;
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int64_t dts;
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unsigned int cache_size;
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} MXGContext;
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static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap)
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{
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AVStream *video_st, *audio_st;
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MXGContext *mxg = s->priv_data;
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/* video parameters will be extracted from the compressed bitstream */
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video_st = avformat_new_stream(s, NULL);
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if (!video_st)
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return AVERROR(ENOMEM);
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video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
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video_st->codec->codec_id = CODEC_ID_MXPEG;
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avpriv_set_pts_info(video_st, 64, 1, 1000000);
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audio_st = avformat_new_stream(s, NULL);
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if (!audio_st)
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return AVERROR(ENOMEM);
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audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
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audio_st->codec->channels = 1;
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audio_st->codec->sample_rate = 8000;
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audio_st->codec->bits_per_coded_sample = 8;
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audio_st->codec->block_align = 1;
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avpriv_set_pts_info(audio_st, 64, 1, 1000000);
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mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
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mxg->buffer_size = 0;
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mxg->dts = AV_NOPTS_VALUE;
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mxg->cache_size = 0;
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return 0;
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}
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static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
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{
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for (; p < end - 3; p += 4) {
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uint32_t x = *(uint32_t*)p;
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if (x & (~(x+0x01010101)) & 0x80808080) {
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if (p[0] == 0xff) {
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return p;
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} else if (p[1] == 0xff) {
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return p+1;
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} else if (p[2] == 0xff) {
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return p+2;
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} else if (p[3] == 0xff) {
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return p+3;
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}
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}
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}
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for (; p < end; ++p) {
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if (*p == 0xff) return p;
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}
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return end;
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}
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static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
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{
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MXGContext *mxg = s->priv_data;
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unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
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unsigned int soi_pos;
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int ret;
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/* reallocate internal buffer */
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if (current_pos > current_pos + cache_size)
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return AVERROR(ENOMEM);
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if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
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mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
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current_pos + cache_size +
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FF_INPUT_BUFFER_PADDING_SIZE);
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if (!mxg->buffer)
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return AVERROR(ENOMEM);
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mxg->buffer_ptr = mxg->buffer + current_pos;
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if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
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/* get data */
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ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
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cache_size - mxg->cache_size);
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if (ret < 0)
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return ret;
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mxg->cache_size += ret;
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return ret;
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}
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static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
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{
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int ret;
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unsigned int size;
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uint8_t *startmarker_ptr, *end, *search_end, marker;
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MXGContext *mxg = s->priv_data;
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while (!s->pb->eof_reached && !s->pb->error){
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if (mxg->cache_size <= OVERREAD_SIZE) {
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/* update internal buffer */
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ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
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if (ret < 0)
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return ret;
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}
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end = mxg->buffer_ptr + mxg->cache_size;
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/* find start marker - 0xff */
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if (mxg->cache_size > OVERREAD_SIZE) {
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search_end = end - OVERREAD_SIZE;
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startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
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} else {
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search_end = end;
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startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
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if (startmarker_ptr >= search_end - 1 ||
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*(startmarker_ptr + 1) != EOI) break;
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}
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if (startmarker_ptr != search_end) { /* start marker found */
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marker = *(startmarker_ptr + 1);
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mxg->buffer_ptr = startmarker_ptr + 2;
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mxg->cache_size = end - mxg->buffer_ptr;
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if (marker == SOI) {
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mxg->soi_ptr = startmarker_ptr;
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} else if (marker == EOI) {
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if (!mxg->soi_ptr) {
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av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
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continue;
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}
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pkt->pts = pkt->dts = mxg->dts;
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pkt->stream_index = 0;
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pkt->destruct = NULL;
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pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
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pkt->data = mxg->soi_ptr;
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if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
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if (mxg->cache_size > 0) {
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memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
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}
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mxg->buffer_ptr = mxg->buffer;
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}
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mxg->soi_ptr = 0;
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return pkt->size;
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} else if ( (SOF0 <= marker && marker <= SOF15) ||
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(SOS <= marker && marker <= COM) ) {
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/* all other markers that start marker segment also contain
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length value (see specification for JPEG Annex B.1) */
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size = AV_RB16(mxg->buffer_ptr);
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if (size < 2)
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return AVERROR(EINVAL);
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if (mxg->cache_size < size) {
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ret = mxg_update_cache(s, size);
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if (ret < 0)
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return ret;
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startmarker_ptr = mxg->buffer_ptr - 2;
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mxg->cache_size = 0;
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} else {
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mxg->cache_size -= size;
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}
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mxg->buffer_ptr += size;
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if (marker == APP13 && size >= 16) { /* audio data */
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/* time (GMT) of first sample in usec since 1970, little-endian */
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pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
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pkt->stream_index = 1;
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pkt->destruct = NULL;
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pkt->size = size - 14;
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pkt->data = startmarker_ptr + 16;
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if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
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if (mxg->cache_size > 0) {
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memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
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}
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mxg->buffer_ptr = mxg->buffer;
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}
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return pkt->size;
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} else if (marker == COM && size >= 18 &&
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!strncmp(startmarker_ptr + 4, "MXF", 3)) {
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/* time (GMT) of video frame in usec since 1970, little-endian */
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mxg->dts = AV_RL64(startmarker_ptr + 12);
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}
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}
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} else {
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/* start marker not found */
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mxg->buffer_ptr = search_end;
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mxg->cache_size = OVERREAD_SIZE;
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}
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}
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return AVERROR_EOF;
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}
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static int mxg_close(struct AVFormatContext *s)
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{
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MXGContext *mxg = s->priv_data;
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av_freep(&mxg->buffer);
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return 0;
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}
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AVInputFormat ff_mxg_demuxer = {
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.name = "mxg",
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.long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"),
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.priv_data_size = sizeof(MXGContext),
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.read_header = mxg_read_header,
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.read_packet = mxg_read_packet,
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.read_close = mxg_close,
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.extensions = "mxg"
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};
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