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• ffmpeg generate first non black frame

  17 octobre 2019, par Milousel

  I get via readstream video from AWS server. I modify it into different format and save it back into server. After that I want to create non black image from first frame of this video. So I need to check if first frame is black or not.

  ffmpeg(stream)
  
          .size('1320x438')
  
          .videoCodec('libx264')
  
          .toFormat('avi')
  
          .output(fileName)
  
          .on('end', function() {
  
            console.log('Finished processing video');
  
            const params = {
  
              Body: fs.createReadStream(fileName),
  
              Bucket: videoBucket,
  
              Key: 'test/modification/' + fileName,
  
            };
  
            s3.putObject(params, (err, data) => {
  
              if (err) {
  
                console.log(err);
  
              }
  
            });
  
          })
  
          .output(screensName + '.jpg')
  
          .outputOptions(
  
            '-frames',
  
            '1', // Capture just one frame of the video
  
          )
  
          .on('end', function() {
  
            console.log('Finished processing screenshot');
  
            const params = {
  
              Body: fs.createReadStream(screensName + '.jpg'),
  
              Bucket: videoBucket,
  
              Key: 'test/shots/' + screensName + '.jpg',
  
            };
  
            s3.putObject(params, (err, data) => {
  
              if (err) {
  
                console.log(err);
  
              }
  
            });
  
          })
  
          .run();

• Is there a way to detect black on FFMPEG video files

  22 novembre 2019, par A Person

  I am trying to run a QC check on my video files.

  I know that there is a way to detect black frame or audio loss in a video file. Can anyone help me with how the syntax is written ?

  I have tried doing the following but I am having issues as I do not know how to tell from the output.

  ffmpeg -i inputfile.mxf -vf blackdetect=d=0.1:pix_th=.1 -f rawvideo -y /dev/null

  Also is there ay ways to check if I have any packets that are in error by using ffprobe or ffmpeg

  I also do not understand waht this 0.1:pix_th=.1 is doing ?

  EDIT* :

  I have used this command now

  ffmpeg -i 01.mxf -vf blackdetect=d=0:pix_th=.01 -f rawvideo -y /NUL

  this gives me

  [blackdetect @ 000001a2ed843740] black_start:0.04 black_end:2

  black_duration:1.96

  [mpeg2video @ 000001a2ed86efc0] ac-tex damaged at 45 304.08

  bitrate=829328.3kbits/s dup=1 drop=0 speed= 5.6x

  However, the actual video has more than this for the black frame.

  is there a way to tell it to continue looking at the video and get all black frames, not just the first instance.

• Trying to concatenate 11 seconds of black video onto the end of a 5 min video. Getting non-monotonous DTS in output stream error

  14 janvier 2020, par TidusWulf

  I have a video shot from my smartphone that is 3840x2160@57.74. Originally, it was exactly 5 minutes long. I replaced the audio with a music file that is 5 minutes and 11 seconds using ffmpeg -i video.mp4 -i audio.mp3 -c copy -map 0:v:0 -map 1:a:0 output.mp4 I expected 11 seconds of black at the end, but instead the video output freezes on the last frame for 11 seconds. There’s definitely something funky going on because when I try to upload to youtube, it only sees the first 5 minutes. The last 10 seconds of audio get dropped.

  I tried making a second black clip with ffmpeg -f lavfi -i color=c=black:s=uhd2160:r=57.74 -t 11 -pix_fmt yuv420p blk2.mp4. When I try to concat the two files with ffmpeg -f concat -safe 0 -i list.txt -c copy teacup6.mp4 I get a huge list of errors such as [mp4 @ 00000166fda994c0] Non-monotonous DTS in output stream 0:0; previous: 27002920, current: 3728954; changing to 27002921. This may result in incorrect timestamps in the output file. for what appears to be about 11 seconds worth of frames, so basically the entire 11 second black clip. When I play it in VLC it goes black, but I suspect it’s not actually processing/playing 11 seconds of good black video because if I click along the track timeline, visual glitches start happening in the canvas.

  Here is what ffmpeg tells me about my inputs and outputs as far as framerate, pixel format, etc.

  [mov,mp4,m4a,3gp,3g2,mj2 @ 00000239e6cb2880] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'list.txt':
 Duration: N/A, start: -0.023021, bitrate: 72244 kb/s
   Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 3840x2160, 71994 kb/s, SAR 1:1 DAR 16:9, 57.74 fps, 59 tbr, 90k tbn, 180k tbc
   Metadata:
     handler_name    : VideoHandle
   Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 250 kb/s
   Metadata:
     handler_name    : SoundHandler
Output #0, mp4, to 'teacup5.mp4':
 Metadata:
   encoder         : Lavf58.35.102
   Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 71994 kb/s, 57.74 fps, 59 tbr, 90k tbn, 90k tbc
   Metadata:
     handler_name    : VideoHandle
   Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 250 kb/s
   Metadata:
     handler_name    : SoundHandler
Stream mapping:
 Stream #0:0 -> #0:0 (copy)
 Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help

  alternatively, I tried to make a black 3840x2160 png file and create an 11 second slideshow. It didn’t turn out any better. I tried a single image for 11 seconds @ 57.74fps, I also tried a looping slideshow of that one image, looping on every single frame, at 57.74 fps. I should note that wether a slideshow or a color generator, the filesize for the 11 seconds of black comes out to about 160KB. Strangely small in my opinion, but I was chalking it up to a good compression algorithm.

  I tried to do this in Da Vinci Resolve 16.1 instead and the video wouldn’t play. I also couldn’t find a way to maintain the same unusual 57.74 framerate with the free version, so it was undesirable anyway. I tried to re-process using Handbrake, but it threw an error. The output of the Handbrake processed video file also gets stuck on the last frame of the video, instead of going to black.