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• FFMPEG : MP4 videos are not playing properly in iPhone, iPod, iPad

  26 janvier 2020, par Shakti Singh

  I am converting videos from m4v, flv to MP4 for iPhone, iPod, iPad.

  I am using the below command to convert these videos

  ffmpeg -y -i video_1336500693.m4v -vcodec libx264 -vpre slow -vpre
  ipod640 -b 250k -bt 50k -acodec libfaac -ab 56k -ac 2 -s 480x320
  video_1336500693.mp4

  The video part of this mp4 file is working fine but the audio is not working properly. I am using HTML5 for this.

  The audio works for first 8-10 seconds but after that audio does not work and the strange thing is if I jump to forward or backward the audio works.

  Can anyone suggest what’s going wrong ?

• Python source code to convert all videos of .avi to .mp4 at a time

  4 juin 2018, par vikash tiwari

  I want to convert nearly 900 videos from .avi to .mp4 . I am currently using ffmpeg to convert a video but this is taking a lot time as i have to manually enter each file name after one step . I m new to python . So is there a way to write a python code that could take all the videos of .avi format from a directory and convert them into .mp4 and store them into a specified directory ? Any help would be highly appreciated .
  Right now i m using this command from my window command prompt to convert the files .
  ffmpeg -i output.avi -codec copy output.mp4

  The code i came up with to do this at a time is :
  for i in .avi ; do
  ffmpeg -i "$i" -codec copy "$i%..mp4"
  done
  But it is showing error in my window terminal

• 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