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• speedhq : fix decoding artifacts

  18 février 2017, par Steinar H. Gunderson

  speedhq : fix decoding artifacts
  The quantization table is stored in the natural order, but when we
  
  access it, we use an index that’s in zigzag order, causing us to read
  
  the wrong value. This causes artifacts, especially in areas with
  
  horizontal or vertical edges. The artifacts look a lot like the
  
  DCT ringing artifacts you’d expect to see from a low-bitrate file,
  
  but when comparing to NewTek’s own decoder, it’s obvious they’re not
  
  supposed to be there.
  Fix by simply storing the scaled quantization table in zigzag order.
  
  Performance is unchanged.
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/speedhq.c

• file sequence (%d) not working when increased to 3 digits FFMPEG

  13 avril 2018, par Junaid Farooq

  I have this kind of image sequence in my folder.

  113.jpg  119.jpg  125.jpg  131.jpg  164.jpg  17.jpg   175.jpg  180.jpg  23.jpg  29.jpg  35.jpg  68.jpg  74.jpg  80.jpg  CURRENT
  
  114.jpg  120.jpg  126.jpg  132.jpg  165.jpg  170.jpg  176.jpg  181.jpg  24.jpg  30.jpg  36.jpg  69.jpg  75.jpg  81.jpg  list.txt
  
  115.jpg  121.jpg  127.jpg  133.jpg  166.jpg  171.jpg  177.jpg  19.jpg   25.jpg  31.jpg  37.jpg  70.jpg  76.jpg  82.jpg  testingplease.mp4
  
  116.jpg  122.jpg  128.jpg  161.jpg  167.jpg  172.jpg  178.jpg  20.jpg   26.jpg  32.jpg  65.jpg  71.jpg  77.jpg  83.jpg
  
  117.jpg  123.jpg  129.jpg  162.jpg  168.jpg  173.jpg  179.jpg  21.jpg   27.jpg  33.jpg  66.jpg  72.jpg  78.jpg  84.jpg
  
  118.jpg  124.jpg  130.jpg  163.jpg  169.jpg  174.jpg  18.jpg   22.jpg   28.jpg  34.jpg  67.jpg  73.jpg  79.jpg  85.jpg

  When I run this command to create a video file

  ffmpeg -r 6 -i /storage/taked-qzaxs/extract/1239/%d.jpg -c:v h264_nvenc -r 6 -preset slow -bufsize 1000k -pix_fmt yuv420p -y /storage/taked-qzaxs/extract/1239/testingplease.mp4

  It throws me such error as

  [image2 @ 0x55ad2ff3d460] Could find no file with path '/storage/taked-qzaxs/extract/1239/%d.jpg' and index in the range 0-4
  
  /storage/taked-qzaxs/extract/1239/%d.jpg: No such file or directory

  Whereas the same command works fine when there are only 10 or 15 images, and image number is within 2 digits range. I don’t know what is wrong with this command. I am using %d, which means it should take all natural numbers in sort form.

• ffmpeg concat .dv without errors or loss of audio sync

  29 mars 2022, par Dave Lang

  I'm ripping video from a bunch of ancient MiniDV tapes using, after much trial and error, some almost as ancient Mac hardware and iMovie HD 6.0.5. This is working well except that it will only create a contiguous video clip of about 12.6 GB in size. If the total video is larger than that, it creates a second clip that is usually about 500 MB.

  


  I want to join these two clips in the "best" way possible - meaning with ffmpeg throwing as few errors as possible, and the audio / video staying in sync.

  


  I'm currently using the following command line in a bash shell :

  


  for f in *.dv ; do echo file '$f' >> list.txt ; done && ffmpeg -f concat -safe 0 -i list.txt -c copy stitched-video.dv && rm list.txt

  


  This seems to be working well, and using the 'eyeball' check, sync seems to be preserved.

  


  However, I do get the following error message when ffmpeg starts in on the second file :

  


  Non-monotonous DTS in output stream 0:1 ; previous : 107844491, current : 107843736 ; changing to 107844492. This may result in incorrect timestamps in the output file.

  


  Since I know just enough about ffmpeg to be dangerous, I don't understand the significance of this message.

  


  Can anyone suggest changes to my ffmpeg command that will fix whatever ffmpeg is telling me is going wrong ?

  


  I'm going to be working on HD MiniDV tapes next, and, because they suffer from numerous dropouts, my task is going to become more complex, so I'd like to nail this one.

  


  Thanks !

  


  as suggested below ffprobe for the two files

  


  Input #0, dv, from 'file1.dv' : Metadata : timecode : 00:00:00 ;22 Duration : 00:59:54.79, start : 0.000000, bitrate : 28771 kb/s Stream #0:0 : Video : dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1 : Audio : pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s

  


  Input #0, dv, from 'file2.dv' : Metadata : timecode : 00:15:06 ;19 Duration : 00:02:04.09, start : 0.000000, bitrate : 28771 kb/s Stream #0:0 : Video : dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1 : Audio : pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s