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• How to stitch(concat) two transport stream with two different resolution and I-frame slices format without loosing resolution and slices information

  2 octobre 2019, par ART

  I have been trying to test a use case with steam captured from multimedia device and that didn't work. And then I have been trying to create this specific transport stream for like two days now without success, so requesting some help.

  



  I need to create transport stream with two different resolution and two different slicing format.

  



  I divided the task in following steps and in last two steps I need help.

  



  Step 1 : Download sample video with resolution : 1920x1080.
  
 I downloaded big buck bunny mp4 .

  



  Step 2 : Create transport stream with following
  
resolution : 1920x720, H264 I frame slices per frame : 1
  
I used following ffmpeg commands to do that.

  



  #Rename file to input.mp4
$ mv bbb_sunflower_1080p_30fps_normal.mp4 input.mp4
#Extract transport stream
$ ffmpeg -i input.mp4 -c copy first.ts


  



  first.ts is having 1980x720 resolution and one H264 I slice per frame.

  



  Step 3 : Create another transport stream with smaller resolution using following commands

  



  #Get mp4 with lower resolution.
$ ffmpeg -i input.mp4 -s 640x480 temp.mp4
#Extract trans port stream from mp4
$ ffmpeg -i temp.mp4 -c copy low_r.ts


  



  Step 4 : Edit(and re-encode ?) low_r.ts to have two H264 I frame slices.
I used following command to achieve it.

  



  $ x264 --slices 4 low_r.ts -o second.ts


  



  However when I play this second.ts on vlc using following command it doesn't play

  



  $ vlc ./second.ts 


  



  And using Elacard StreamEye software when I analyze the transport stream I see that it has 4 H264 I slices in only two times other than that lot of H264 p slices and H264 B slices. 
Need help here to figure out why second.ts doesn't play and why slicing is not correct.

  



  Step 5 : Combine both the transport stream without loosing resolution and slicing information.
Don't know command for this. Need help here.
I tried ffmpeg but that combines two stream with different resolution and makes one file with one resolution.

  



  Any suggestions/pointers would help me proceed. Let me also know if any of the above steps are not fine too.

  


• Transparent movie with video format qtrle unplayable in QuickTime

  1er janvier 2021, par 220284

  I use the python library Manim to generate mathematical animations. I want to use the animations in Keynote presentations. Manim has the option to produce movie clips with a transparent background. Unfortunately, QuickTime won't play the files generated by Manim. Here's the metadata for a file produced by Manim

  


  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf58.45.100
  Duration: 00:01:07.00, start: 0.000000, bitrate: 6635 kb/s
    Stream #0:0: Video: qtrle (rle  / 0x20656C72), argb(progressive), 1280x960, 6632 kb/s, 60 fps, 60 tbr, 15360 tbn, 15360 tbc (default)
    Metadata:
      handler_name    : VideoHandler
      encoder         : Lavc58.91.100 qtrle


  


  Ideally, I would want to use ffmpeg to turn these files into movie clips with transparent background which are playable in QuickTime. Can this be done ?

  


  As a work around, I imported the files into Final Cut Pro and exported them again using Apple Pro Res 4444, but this resulted in huge file sizes.

  


• Encoding a readable H264 4:2:2 movie by QuickTime using FFMPEG

  12 octobre 2019, par Tanos

  I am aware of the solution with -pix_fmt yuv420p as stated here but that encodes it at 4:2:0. I would like the encode to be a 4:2:2 and changing to -pix_fmt yuv422p doesn’t work. I’ve tried different containers with out lack. What definitely works is ’prores’ but I don’t need such a high bitrate video.

  For context, I create timelapses from photos and I would like to be able to use Quick Look or Quick Time for playback.

  I use mediainfo to check the video’s attributes.