pts

I've seen a number of questions regarding video PTS values not starting at zero, or asking how to make them start at zero. I'm aware that using ffmpeg I can do something like ffmpeg -i <video> -vf="setpts=PTS-STARTPTS" <output> to fix this kind of thing However it's my understanding that PTS values don't have to start at zero. For instance, if you join a live stream then odds are it has been going on for an hour and the PTS is already somewhere around 3600000+ but your video player faithfully displays everything just fine. Therefore I would expect there to be no problem if I intentionally

How to calculate correct PTS value for frame before encoding in FFmpeg C API? For encoding I'm using function avcodec_encode_video2 and then write it by av_interleaved_write_frame . I found some formulas, but no one of them doesn't work. In doxygen example they are using frame->pts = 0; for (;;) { // encode & write frame // ... frame->pts += av_rescale_q(1, video_st->codec->time_base, video_st->time_base); } This blog says that formula must be like this: (1 / FPS) * sample rate * frame number Someone uses only frame number to set pts: frame->pts = videoCodecCtx->frame_number; Or alternative

I had fps issues when transcoding from avi to mp4(x264). Eventually the problem was in PTS and DTS values, so lines 12-15 where added before av_interleaved_write_frame function: 1. AVFormatContext* outContainer = NULL; 2. avformat_alloc_output_context2(&outContainer, NULL, "mp4", "c:\\test.mp4"; 3. AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_H264); 4. AVStream *outStream = avformat_new_stream(outContainer, encoder); 5. // outStream->codec initiation 6. // ... 7. avformat_write_header(outContainer, NULL); 8. // reading and decoding packet 9. // ... 10. avcodec_encode_video2(outStream-

Final Exam for Statistical Learning Summer 2019 Name____________ Student ID#_____________ Part I. (10 pts) True/False? In the following problems, determine whether the statement is true or false. If it is false, please correct it. 1. In the ANOVA table for a linear regression model, the F statistic checks the significance of the model. The F statistic follows the F distribution with degrees of freedom K and n-K-1, where n is the sample size and K equals the number of independent variables. _______ 2. An application of the linear regression model with an intercept and 9 independent variables

主要介绍直线、矩形框、椭圆和字体注释。 import numpy as np import cv2 # Create a black image img=np.zeros((512,512,3), np.uint8) #直线 cv2.line(img,(0,0),(511,511),(255,0,0),5) #矩形 cv2.rectangle(img,(384,0),(510,128),(0,255,0),3) #圆形 cv2.circle(img,(447,63), 63, (0,0,255), -1) #椭圆 cv2.ellipse(img,(256,256),(100,50),0,0,180,255,-1) #多边形 pts=np.array([[10,5],[20,30],[70,20],[50,10]], np.int32) pts=pts.reshape((-1,1,2)) cv2.polylines(img,[pts],True,(0,255,255)) #添加文字 cv2.putText(img,'OpenCV',(10,500), cv2.FONT_HERSHEY_SIMPLEX, 4,(255,255,255),2) cv2.imshow('image',img) 来源： https://blog.csdn.net/XIAOYUE3035/article