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• ios http live black screen

  11 mars 2013, par jagsler

  In my ios app I am trying to play videos using http live streaming. The playing goes well until I decide to use the scrubber and skip to some point that hasn't buffered yet. From that moment the audio goes on but the videos goes black.

  I've converted my .MP4 videos with the following command :

  avconv -y -i video.mp4 -f mpegts -acodec libmp3lame -ar 48000 -ab 64k -s 640x480 -vcodec libx264 -b 64k -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 0 -refs 0 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate 64k -bufsize 64k -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 30 -qmax 51 -qdiff 4 -level 30 -aspect 640:480 -g 30 -async 2 sample_64.ts

  I did this with multiple bitrates (64, 150, 240, 440 and 640) and created one .m3u8 that contains the different streams. After converting I used the mediafilesegmenter to split the video in segments of each 10 seconds.

  After scrubbing the following appears in the output window :

  2013-03-08 17:30:21.827 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Disabling autoplay for pause
  
  2013-03-08 17:30:21.827 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Disabling autoplay
  
  2013-03-08 17:30:21.977 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamUnlikelyToKeepUp: 1 -> 0
  
  2013-03-08 17:30:21.978 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:21.978 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamRanDry: 0 -> 1
  
  2013-03-08 17:30:21.980 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Took background task assertion (32) for playback stall
  
  2013-03-08 17:30:21.981 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:22.634 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamUnlikelyToKeepUp: 0 -> 0
  
  2013-03-08 17:30:22.634 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: _streamRanDry: 0 -> 1
  
  2013-03-08 17:30:22.667 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Skipping autoplay, disabled (for current item: 1, on player: 0)
  
  2013-03-08 17:30:22.769 Geschiedenis Trainer[88129:19a03] [MPAVController] Autoplay: Ending background task assertion (32) for playback stall

  The code for my videoplayer :

  self.streamPlayer = [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
  
  [self.view addSubview:self.streamPlayer.view];
  
  [self.streamPlayer setFullscreen:YES animated:YES];

  This problem does not occur when skipping to a point that has already been buffered.

• ffmpeg return black and white image

  16 décembre 2011, par njai

  Video capture device is kworld dvd maker 2 (em2861)
  It returns the image in "black and white" with green line at the bottom of screen ; but when I tested it with webcam, it worked properly.

  Here is 30s video. http://www.youtube.com/watch?v=7q2wFGVwGGI

  How can I convert it to color ?

  [root@localhost ~]# ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -y output.mp4
  
  ffmpeg version git-2011-11-05-5fd1a69, Copyright (c) 2000-2011 the FFmpeg developers
  
  built on Nov  5 2011 21:10:52 with gcc 4.4.4 20100726 (Red Hat 4.4.4-13)
  
  configuration: --enable-libx264 --enable-gpl --enable-libvpx
  
  libavutil    51. 23. 0 / 51. 23. 0
  
  libavcodec   53. 27. 0 / 53. 27. 0
  
  libavformat  53. 18. 0 / 53. 18. 0
  
  libavdevice  53.  4. 0 / 53.  4. 0
  
  libavfilter   2. 47. 0 /  2. 47. 0
  
  libswscale    2.  1. 0 /  2.  1. 0
  
  libpostproc  51.  2. 0 / 51.  2. 0
  
  [video4linux2,v4l2 @ 0x2a64780] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
  Duration: N/A, start: 1320637788.113946, bitrate: 165888 kb/s
  
  Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 720x576, 165888 kb/s, 25 tbr, 1000k tbn, 25 tbc
  
  Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yuv420p'
  
  [buffer @ 0x2a63920] w:720 h:576 pixfmt:yuyv422 tb:1/1000000 sar:0/1 sws_param:
  
  [buffersink @ 0x2a63cc0] auto-inserting filter 'auto-inserted scale 0' between the filter    'src' and the filter 'out'
  
  [scale @ 0x2a64560] w:720 h:576 fmt:yuyv422 -> w:720 h:576 fmt:yuv420p flags:0x4
  
  Output #0, mp4, to 'output.mp4':
  
  Metadata:
  
  encoder         : Lavf53.18.0
  
  Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 720x576, q=2-31, 200 kb/s, 25    tbn, 25 tbc
  
  Stream mapping:
  
  Stream #0.0 -> #0.0 (rawvideo -> mpeg4)
  
  Press [q] to stop, [?] for help
  
  frame=  969 fps= 25 q=31.0 Lsize=    1547kB time=00:00:38.76 bitrate= 327.0kbits/s    
  
  video:1538kB audio:0kB global headers:0kB muxing overhead 0.561411%

• 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.