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• FFMPEG Crop with side by side merge

  24 juin 2019, par Alan

  I am trying to create a shell/ffmpeg script that can show multiple files after they have been processed using different filters in a side by side / tiled way. An example of desired output would be : https://www.youtube.com/watch?v=DoPuhMRYem4.

  In order to create the desired output I need to crop off the right half of video1 and the left half of video2 and then join them back with [video1+video2] side by side. I have played around with a bunch of different ways of joining them, this does OK :

  ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex "
  
  nullsrc=size=800x400 [background];
  
  [0:v] setpts=PTS-STARTPTS, scale=400x400 [left];
  
  [1:v] setpts=PTS-STARTPTS, scale=400x400 [right];
  
  [background][left]       overlay=shortest=1       [background+left];
  
  [background+left][right] overlay=shortest=1:x=400 [left+right]
  
  " -map '[left+right]' joined.mp4

  How can I modify this to detect the video width (they won’t always be the same width), divide the width in half and crop either the left or right sides off ?

• FFMPEG corrupted frame when streaming in UDP (MPEGTS)

  17 décembre 2020, par user37616

  I am working on a screen streaming program, till now, I can capture and encode my screen into a video perfectly. 
However, whenever I try to stream it over LAN, and play using Mplayer, it is able to run in simple desktop (text document, etc...) but when I try to play video the frame stated to corrupted until I quit the video (this video cause the most corrupted frame https://www.youtube.com/watch?v=1La4QzGeaaQ&t=230s)

  



  I am not really sure why when streaming, I got corrupted frame with the youtube video but when save it to a file (change URL from udp ://192.168.1.xxx:YYYY to file name C :\Test.ts) there were no corrupted frame at all.
 My Mplayer log :

  



  `V:   0.0 1563/1563 51% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 23 51, bytestream -64
[h264 @ 0000000001d04940]concealing 2066 DC, 2066 AC, 2066 MV errors in I frame
V:   0.0 1564/1564 51% 43%  0.0% 0 0
[h264 @ 0000000001d04940]concealing 7598 DC, 7598 AC, 7598 MV errors in P frame
V:   0.0 1652/1652 50% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 26 49, bytestream -55
[h264 @ 0000000001d04940]concealing 2303 DC, 2303 AC, 2303 MV errors in I frame
V:   0.0 1653/1653 50% 43%  0.0% 0 0
[h264 @ 0000000001d04940]concealing 7727 DC, 7727 AC, 7727 MV errors in P frame
V:   0.0 1741/1741 49% 43%  0.0% 0 0
[h264 @ 0000000001d04940]Invalid NAL unit 0, skipping.
[h264 @ 0000000001d04940]error while decoding MB 65 62, bytestream -57
[h264 @ 0000000001d04940]concealing 704 DC, 704 AC, 704 MV errors in I frame
V:   0.0 1742/1742 49% 43%  0.0% 0 0`


  



  Stream initialize code

  



  static void Stream_ini(const char *Url, AVFormatContext *&ofmt_ctx, AVCodec *codec, AVCodecContext *c, AVStream *&out_stream)
{
    int ret;


    avformat_alloc_output_context2(&ofmt_ctx, NULL, "mpegts", Url);
    out_stream = avformat_new_stream(ofmt_ctx, codec)
    out_stream->codec = c;
    av_dump_format(ofmt_ctx, 0, Url, 1);


    if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
        out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    if (!(ofmt_ctx->flags & AVFMT_NOFILE))
    {
        ret = avio_open(&ofmt_ctx->pb, Url, AVIO_FLAG_WRITE);
        if (ret < 0)
        {
            printf("Could not open output URL '%s'", Url);
            return;
        }
    }


    ret = avformat_write_header(ofmt_ctx, NULL);

    if (ret < 0)
    {
        printf("Error occurred when opening output URL\n");
        return;
    }


}


  



  this code will get the captured screen and send it to encoder :

  



  ScreenCap.load_screen_data(inFrame,timmer)  // this will capture screen and return the time and AVFrame for encoding
sws_scale(ctx, inFrame->data, inFrame->linesize, 0,c->height, frame->data, frame->linesize);

frame->pts = (timmer - first_frame_time) / fps;
EncodeToPkT(c, frame, pkt, ofmt_ctx,out_stream);

av_frame_free(&inFrame);


  



  the AVFrame will then be send to encoder using avcodec_send_frame() to get Packet data and av_interleaved_write_frame() to stream it over LAN.

  



  All error check are removed for simplicity

  



  Also, this is my AVCodecContex setting for the encoder :

  



  c->bit_rate = 15000000;
c->width = 1920;
c->height = 1080;
c->time_base = AVRational{ 1, 90 };
c->framerate = AVRational{ 90, 1 };
c->gop_size = 90;
c->max_b_frames = 0;
c->pix_fmt = AV_PIX_FMT_RGB0;


  



  I also notice it only happen when I increase encoder bitrate (15 MBIT) but when lower it down to (10 MBIT) it happen less. And when lower it down to 2 MBIT the corrupted frame not happen anymore however the quality is really bad.
  
I test the streaming in LAN using : PC -> cable ->laptop, PC->wireless->laptop, PC->Virtual PC, PC only (enter PC IP address in both program and Mplayer), all got the same result.

  



  I also test my DXGICap.load_screen_data function by make it output raw image and there were no corrupted image at all

  



  Does anybody have an idea why.

  



  Thank Nam.

  


• Raspberry PI3 records video without quality from IP Camera

  22 avril 2018, par Marcos da Cruz Sibilio Jr.

  I try to record video using : raspberry pi 3, IP Camera and ffmpeg command.
  I installed ffmpeg by surce code for enable libx264 it works but not very well.
  I use the syntax (in raspberry command line) :

  ffmpeg -i "rtsp://192.168.100.108:554/user=admin&password=admin&channel=1&stream=0.sdp?" -t 00:01:00 -an -y -framerate 25 -vcodec:a copy -vcodec:a h264  video_teste.h264

  after that I copy the file for my notebook and run :

  MP4Box -fps 30 -add video_teste.h264 v.mp4

  after tha I can watch the video (v.mp4) but the image is like that :
  image by video recorded

  command ffmpeg retuns this lines :
  ffmpeg results

  I tried some configurations for ffmpeg, tried the resolution camera (D1 and 720p), tried to record with opencv (it is installed too).
  I need to record h264 video in raspberry Pi (I will use extern HD for record the videos) and transfer to my server by ftp, but it is necessary that the video quality is good.