inline void CvCapture_FFMPEG::seek(s64 _frame_number)
{
_frame_number = std::min(_frame_number, get_total_frames());
int delta = 16;
// if we have not grabbed a single frame before first seek, let's read the first frame
// and get some valuable information during the process
if( first_frame_number < 0 && get_total_frames() > 1 )
grabFrame();
for(;;)
{
s64 _frame_number_temp = std::max(_frame_number-delta, (s64)0);
double sec = (double)_frame_number_temp / get_fps();
s64 time_stamp = ic->streams[video_stream]->start_time;
double time_base = r2d(ic->streams[video_stream]->time_base);
time_stamp += (s64)(sec / time_base + 0.5);
if (get_total_frames() > 1) av_seek_frame(ic, video_stream, time_stamp, AVSEEK_FLAG_BACKWARD);
avcodec_flush_buffers(ic->streams[video_stream]->codec);
if( _frame_number > 0 )
{
grabFrame();
if( _frame_number > 1 )
{
frame_number = dts_to_frame_number(picture_pts) - first_frame_number;
//printf("_frame_number = %d, frame_number = %d, delta = %d\n",
// (int)_frame_number, (int)frame_number, delta);
if( frame_number < 0 || frame_number > _frame_number-1 )
{
if( _frame_number_temp == 0 || delta >= INT_MAX/4 )
break;
delta = delta < 16 ? delta*2 : delta*3/2;
continue;
}
while( frame_number < _frame_number-1 )
{
if(!grabFrame())
break;
}
frame_number++;
break;
}
else
{
frame_number = 1;
break;
}
}
else
{
frame_number = 0;
break;
}
}
}
inline bool CvCapture_FFMPEG::grabFrame()
{
bool valid = false;
int got_picture;
int count_errs = 0;
const int max_number_of_attempts = 1 << 16;
if( !ic || !video_st ) return false;
if( ic->streams[video_stream]->nb_frames > 0 &&
frame_number > ic->streams[video_stream]->nb_frames )
return false;
av_free_packet (&packet);
picture_pts = AV_NOPTS_VALUE_;
unsigned long start;
unsigned long end;
// get the next frame
while (!valid)
{
start = GetTickCount();
//while (1){
int ret = av_read_frame(ic, &packet);
//printf("(%s,%d) Size %d ret %d %d\n", __FUNCTION__, __LINE__, packet.size, ret,
// GetTickCount() - start);
//DumpHex((char *)(packet.data), 20);
if (ret == AVERROR(-1)) continue;
// }
/* else if (ret < 0) break; */
if( packet.stream_index != video_stream )
{
//printf("(%s,%d)\n", __FUNCTION__, __LINE__);
av_free_packet (&packet);
count_errs++;
if (count_errs > max_number_of_attempts)
break;
continue;
}
start = GetTickCount();
// Decode video frame
#if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(53, 2, 0)
avcodec_decode_video2(video_st->codec, picture, &got_picture, &packet);
#elif LIBAVFORMAT_BUILD > 4628
avcodec_decode_video(video_st->codec,
picture, &got_picture,
packet.data, packet.size);
#else
avcodec_decode_video(&video_st->codec,
picture, &got_picture,
packet.data, packet.size);
#endif
//printf("(%s,%d) avcodec_decode_video2 %d\n", __FUNCTION__, __LINE__,
// GetTickCount() - start);
// Did we get a video frame?
if(got_picture)
{
//printf("(%s,%d) got_picture %d\n", __FUNCTION__, __LINE__,
// GetTickCount() - start);
//picture_pts = picture->best_effort_timestamp;
if( picture_pts == AV_NOPTS_VALUE_ )
picture_pts = packet.pts != AV_NOPTS_VALUE_ && packet.pts != 0 ? packet.pts : packet.dts;
frame_number++;
valid = true;
}
else
{
count_errs++;
if (count_errs > max_number_of_attempts)
break;
}
av_free_packet (&packet);
}
if( valid && first_frame_number < 0 )
first_frame_number = dts_to_frame_number(picture_pts);
// return if we have a new picture or not
return valid;
}
bool CvCapture_FFMPEG::grabFrame()
{
bool valid = false;
int got_picture;
int count_errs = 0;
const int max_number_of_attempts = 1 << 16;
if( !ic || !video_st ) return false;
if( ic->streams[video_stream]->nb_frames > 0 &&
frame_number > ic->streams[video_stream]->nb_frames )
return false;
av_free_packet (&packet);
picture_pts = AV_NOPTS_VALUE_;
// get the next frame
while (!valid)
{
int ret = av_read_frame(ic, &packet);
if (ret == AVERROR(EAGAIN)) continue;
/* else if (ret < 0) break; */
if( packet.stream_index != video_stream )
{
av_free_packet (&packet);
count_errs++;
if (count_errs > max_number_of_attempts)
break;
continue;
}
// Decode video frame
#if LIBAVFORMAT_BUILD >= CALC_FFMPEG_VERSION(53, 2, 0)
avcodec_decode_video2(video_st->codec, picture, &got_picture, &packet);
#elif LIBAVFORMAT_BUILD > 4628
avcodec_decode_video(video_st->codec,
picture, &got_picture,
packet.data, packet.size);
#else
avcodec_decode_video(&video_st->codec,
picture, &got_picture,
packet.data, packet.size);
#endif
// Did we get a video frame?
if(got_picture)
{
//picture_pts = picture->best_effort_timestamp;
if( picture_pts == AV_NOPTS_VALUE_ )
picture_pts = packet.pts != AV_NOPTS_VALUE_ && packet.pts != 0 ? packet.pts : packet.dts;
frame_number++;
valid = true;
}
else
{
count_errs++;
if (count_errs > max_number_of_attempts)
break;
}
av_free_packet (&packet);
}
if( valid && first_frame_number < 0 )
first_frame_number = dts_to_frame_number(picture_pts);
// return if we have a new picture or not
return valid;
}
