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• H264 NAL unit header - detect type and bring custom videos in this format

  7 décembre 2015, par user3387542

  On a special interface on my device, I can see the NAL units passing by. Two example files shown below :

  P-Frames:
  
  00 00 00 01 41 FC 0F 90 86 DE F9 E1 4D 37 AE D3 
  
  24 A9 F2 F7 E8 A0 9A 9E B3 FD FE 3A D2 77 3E 79 
  
  8C 93 2D 75 61 60 A0 FA BF CB 46 B6 67 A6 C2 81 
  
  2B 47 A5 A2 71 5D 4F 90 32 14 EE D5 DE 58 3B 6E 
  
  ...
  
  
  
  I-Frames / Key-Frames:
  
  00 00 00 01 65 B8 20 67 FF FE 1E 8A 00 02 05 BE 
  
  4D 49 85 EB FC 9E 44 F7 D0 CE A0 77 25 CD 80 D4 
  
  4A A4 E5 66 EE E7 F9 17 E5 81 DC 94 9C 2B 3C DF 
  
  DE D2 63 CC 89 98 82 4D AF C6 BF E8 3F 0D 3C BE 
  
  ...

  My goal is, to be able to overwrite this data in order to inject / play my own video. So fare so good, seems to work but it doesn’t look good yet. While replayed NAL units, which were previously stored from the very same interface look good, an injected video doesn’t. I think i did not get the right video format yet.
  I used different tools like ffmpeg to convert videos into a h264 format. But the video still never looks fine. I think the issue is with the key-frames. While I see lots of 00 00 00 01 41 parts in the converted videos, i can’t find a 00 00 00 01 65.

  What kind of video format is this ? And how to convert my own videos into this format ? By using ffmpeg or other tools.

  Thanks in advance

• avcodec/pictordec : Remove mid exit branch

  25 novembre 2022, par Michael Niedermayer

  avcodec/pictordec : Remove mid exit branch
  This causes the RLE decoder to exit before applying the last RLE run
  
  All images i tested with are unchanged, this makes the special case
  
  for handling the last run unused for non truncated images.
  Reviewed-by : Peter Ross <pross@xvid.org>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/pictordec.c

• ffmpeg eats up / cannot read variable names from script

  14 avril 2022, par mcExchange

  The following text file ("myTextFile.txt") is used to cut a video into chunks

  


  00:00:00.0 video_name_1.mp4
00:10:00.1 video_name_2.mp4
00:20:00.1 video_name_3.mp4


  


  First columns are time stamps of cutting points [HH:MM:SS.millis].

  


  I use the following command to read the txt file and cut a video called "input_video.mp4" into clips of 10 seconds each

  


  while read line ; do 
  start_time=$(echo $line | cut -d' ' -f1);
  output_name=$(echo $line | cut -d' ' -f2);
  ffmpeg -ss $start_time -t 00:00:10.0 -i input_video.mp4 ${output_name}; 
done < myTextFile.txt


  


  but it's not working. The output filenames are corrupt and I don't know why. I'm not using any special characters in the output filenames. Why is this happening ?

  


  My current work around is printing the last line ("ffmpeg ...") into the console and then paste all commands into the console command and thereby executing them...