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/*
* MxPEG clip file demuxer
* Copyright (c) 2010 Anatoly Nenashev
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/intreadwrite.h"
#include "libavcodec/mjpeg.h"
#include "avformat.h"
#include "avio.h"
#define VIDEO_STREAM_INDEX 0
#define AUDIO_STREAM_INDEX 1
#define DEFAULT_PACKET_SIZE 1024
#define OVERREAD_SIZE 3
typedef struct MXGContext {
uint8_t *buffer;
uint8_t *buffer_ptr;
uint8_t *soi_ptr;
unsigned int buffer_size;
int64_t dts;
unsigned int cache_size;
} MXGContext;
static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
AVStream *video_st, *audio_st;
MXGContext *mxg = s->priv_data;
/* video parameters will be extracted from the compressed bitstream */
video_st = av_new_stream(s, VIDEO_STREAM_INDEX);
if (!video_st)
return AVERROR(ENOMEM);
video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
video_st->codec->codec_id = CODEC_ID_MXPEG;
av_set_pts_info(video_st, 64, 1, 1000000);
audio_st = av_new_stream(s, AUDIO_STREAM_INDEX);
if (!audio_st)
return AVERROR(ENOMEM);
audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
audio_st->codec->channels = 1;
audio_st->codec->sample_rate = 8000;
audio_st->codec->bits_per_coded_sample = 8;
audio_st->codec->block_align = 1;
av_set_pts_info(audio_st, 64, 1, 1000000);
mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
mxg->buffer_size = 0;
mxg->dts = AV_NOPTS_VALUE;
mxg->cache_size = 0;
return 0;
}
static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
{
for (; p < end - 3; p += 4) {
uint32_t x = *(uint32_t*)p;
if (x & (~(x+0x01010101)) & 0x80808080) {
if (p[0] == 0xff) {
return p;
} else if (p[1] == 0xff) {
return p+1;
} else if (p[2] == 0xff) {
return p+2;
} else if (p[3] == 0xff) {
return p+3;
}
}
}
for (; p < end; ++p) {
if (*p == 0xff) return p;
}
return end;
}
static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
{
MXGContext *mxg = s->priv_data;
unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
unsigned int soi_pos;
int ret;
/* reallocate internal buffer */
if (current_pos > current_pos + cache_size)
return AVERROR(ENOMEM);
if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
current_pos + cache_size +
FF_INPUT_BUFFER_PADDING_SIZE);
if (!mxg->buffer)
return AVERROR(ENOMEM);
mxg->buffer_ptr = mxg->buffer + current_pos;
if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
/* get data */ |
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cache_size - mxg->cache_size);
if (ret < 0)
return ret;
mxg->cache_size += ret;
return ret;
}
static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret;
unsigned int size;
uint8_t *startmarker_ptr, *end, *search_end, marker;
MXGContext *mxg = s->priv_data;
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if (mxg->cache_size <= OVERREAD_SIZE) {
/* update internal buffer */
ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
if (ret < 0)
return ret;
}
end = mxg->buffer_ptr + mxg->cache_size;
/* find start marker - 0xff */
if (mxg->cache_size > OVERREAD_SIZE) {
search_end = end - OVERREAD_SIZE;
startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
} else {
search_end = end;
startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
if (startmarker_ptr >= search_end - 1 ||
*(startmarker_ptr + 1) != EOI) break;
}
if (startmarker_ptr != search_end) { /* start marker found */
marker = *(startmarker_ptr + 1);
mxg->buffer_ptr = startmarker_ptr + 2;
mxg->cache_size = end - mxg->buffer_ptr;
if (marker == SOI) {
mxg->soi_ptr = startmarker_ptr;
} else if (marker == EOI) {
if (!mxg->soi_ptr) {
av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
continue;
}
pkt->pts = pkt->dts = mxg->dts;
pkt->stream_index = VIDEO_STREAM_INDEX;
pkt->destruct = NULL;
pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
pkt->data = mxg->soi_ptr;
if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
if (mxg->cache_size > 0) {
memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
}
mxg->buffer_ptr = mxg->buffer;
}
mxg->soi_ptr = 0;
return pkt->size;
} else if ( (SOF0 <= marker && marker <= SOF15) ||
(SOS <= marker && marker <= COM) ) {
/* all other markers that start marker segment also contain
length value (see specification for JPEG Annex B.1) */
size = AV_RB16(mxg->buffer_ptr);
if (size < 2)
return AVERROR(EINVAL);
if (mxg->cache_size < size) {
ret = mxg_update_cache(s, size);
if (ret < 0)
return ret;
startmarker_ptr = mxg->buffer_ptr - 2;
mxg->cache_size = 0;
} else {
mxg->cache_size -= size;
}
mxg->buffer_ptr += size;
if (marker == APP13 && size >= 16) { /* audio data */
/* time (GMT) of first sample in usec since 1970, little-endian */
pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
pkt->stream_index = AUDIO_STREAM_INDEX;
pkt->destruct = NULL;
pkt->size = size - 14;
pkt->data = startmarker_ptr + 16;
if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
if (mxg->cache_size > 0) {
memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
}
mxg->buffer_ptr = mxg->buffer;
}
return pkt->size;
} else if (marker == COM && size >= 18 &&
!strncmp(startmarker_ptr + 4, "MXF", 3)) {
/* time (GMT) of video frame in usec since 1970, little-endian */
mxg->dts = AV_RL64(startmarker_ptr + 12);
}
}
} else {
/* start marker not found */
mxg->buffer_ptr = search_end;
mxg->cache_size = OVERREAD_SIZE;
}
}
return AVERROR_EOF;
}
static int mxg_close(struct AVFormatContext *s)
{
MXGContext *mxg = s->priv_data;
av_freep(&mxg->buffer);
return 0;
}
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.name = "mxg",
.long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"),
.priv_data_size = sizeof(MXGContext),
.read_header = mxg_read_header,
.read_packet = mxg_read_packet,
.read_close = mxg_close,
.extensions = "mxg"
}; |