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• H.264 codec with FMO and data partitioning support ?

  25 avril 2018, par Siego

  For a project I need to use H.264 codec for a error prone environment. For this i want to use FMO and data partitioning. But i cant find a codec that support these features or the extend profile.

  So does anybody know a H.264 libary I can use that support this?

• When compressing a set of images with libx264, why does frame rate affect final output size ?

  3 avril 2018, par jd20

  I'm using ffmpeg to encode a set of images as a short timelapse video, using libx264 codec. My first attempt, I encoded it at 30 FPS, using:

  ffmpeg -r 30 -pattern_type glob -i "*.jpg" -vcodec libx264 -crf 30 -pix_fmt yuv420p output.mp4
  

  With 60 frames, that gives me a 163 KB file that's 2 seconds long. Then I realized I needed it to be slower, so I re-ran the same command, but changed -r to 2. Now I have a file that's 30 seconds long, but the size jumped to 891 KB! The video quality looks perceptually the same.

  How do I encode at a slower frame rate, without the final file size ballooning?

  ---

  Notes: Some theories I had, and things I checked. First, to make sure ffmpeg wasn't duplicating frames in the longer verison, I check the I/P/B counts. The 30 FPS file had:

  [libx264 @ 0x7f9b26001c00] frame I:1     Avg QP:30.67  size: 44649
  [libx264 @ 0x7f9b26001c00] frame P:15    Avg QP:31.19  size:  5471
  [libx264 @ 0x7f9b26001c00] frame B:44    Avg QP:31.45  size:   767
  

  The 2 FPS file had:

  [libx264 @ 0x7fcd32842200] frame I:1     Avg QP:21.29  size: 90138
  [libx264 @ 0x7fcd32842200] frame P:15    Avg QP:22.48  size: 33686
  [libx264 @ 0x7fcd32842200] frame B:44    Avg QP:26.29  size:  6674
  

  So, the I/P/B counts are identical, but the QP is much lower for the 2 FPS file. To offset, I tried increasing -crf for the 2 FPS file, to get about the same target size, but that just gave me a very blurry video (had to go to crf=40). I tried messing with -minrate, -maxrate, -bt, none helped. I'm guessing there is some x264 codec setting which is frame rate dependent, but I'm at a loss trying to figure out which one (from what I understand, constant bitrate is affected by frame rate but CRF should not be, but maybe I'm misunderstanding it.

• ffmpeg settings for high quality youtube videos [migrated]

  1er avril 2018, par pb.

  I am trying to record short video of my desktop and upload it to youtube. The problem is that every time when I upload it to youtube or even dropbox (as video), the quality is much worse.

  My ffmpeg execution:

  ffmpeg -f x11grab -s 1366x768 -r 30 -i :0.0 -codec:v libx264 -crf 10 -bf 20 -flags +cgop -pix_fmt yuv440p -movflags faststart help.mp4
  

  based on:

  ffmpeg -i  -codec:v libx264 -crf 21 -bf 2 -flags +cgop -pix_fmt yuv420p -codec:a aac -strict -2 -b:a 384k -r:a 48000 -movflags faststart .mp4
  

  which I found here

  Original file (.zip): https://www.dropbox.com/s/xlkr83rkqfxon23/help.mp4.zip?dl=0

  File after upload to youtube: https://www.youtube.com/watch?v=ewEUgpXOpmg

  As you can see, I loss quality after upload to youtube.

  Could you help me?
  How should I choose the appropriate parameters to record and upload high quality video?

• Documentations and tutorials for libx264 ?

  28 mars 2018, par David Tree

  I've compiled X264 source code and got libx264.so and x264.h. Surprisingly, I could not find any lib documentation (VideoLan/wiki) except for the header file (x264.h) when I was trying to write a simple program using lib APIs. There are some sample codes on Internet but I do want to know what the lib exactly can do.

  I'm a rookie. Does anyone know if there are good documentations or tutorials for x264?

• desktop recording - ffmpeg settings for high quality youtube videos

  21 mars 2018, par pb.

  I am trying to record short video of my desktop and upload it to youtube. The problem is that every time when I upload it to youtube or even dropbox (as video), the quality is much worse.

  My ffmpeg execution:

  ffmpeg -f x11grab -s 1366x768 -r 30 -i :0.0 -codec:v libx264 -crf 10 -bf 20 -flags +cgop -pix_fmt yuv440p -movflags faststart help.mp4
  

  based on:

  ffmpeg -i  -codec:v libx264 -crf 21 -bf 2 -flags +cgop -pix_fmt yuv420p -codec:a aac -strict -2 -b:a 384k -r:a 48000 -movflags faststart .mp4
  

  which I found here

  Original file (.zip): https://www.dropbox.com/s/xlkr83rkqfxon23/help.mp4.zip?dl=0

  File after upload to youtube: https://www.youtube.com/watch?v=ewEUgpXOpmg

  As you can see, I loss quality after upload to youtube.

  Could you help me?
  How should I choose the appropriate parameters to record and upload high quality video?