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• Ffmpeg adding watermark with qsv hardware acceleration optimize performance

  11 février 2020, par Ksilon

  I add text watermark on video with ffmpeg but i’m new with ffmpeg and try to optimize performance for this.

  My test setup has i5-7500 and Intel HD 630. I tried this code to add watermark on video. If I do not set -hwaccel_output_format to yuv420p or nv12 , it gives error.

  ffmpeg -threads 4 -hwaccel qsv -hwaccel_output_format yuv420p -i "input.mp4" -vf "drawtext=text='TEST':x=(W-tw)/2:y=(H-th)/2:fontfile=arial.ttf:fontsize=250:fontcolor=white@0.4:shadowcolor=black@0.4:shadowx=2:shadowy=2" -c:v h264_qsv "output.mp4"

  When I run this code, Cpu usage 53% / fps = 90-95 / gpu_load(GPU-Z) = 35-38%
  When I changed -threads 1, Cpu usage 35% / fps = 68-72 / gpu_load(GPU-Z) = 28-30%

  Find -async_depth keyword on the Internet and tried it with 5 but nothing happens or I used it wrong.

  How can use more gpu and less cpu for this operation ?

• Creating a video from data of server-side script

  8 mars 2016, par Peter Leupold

  My plan is to display the data that a server-side script generates in a video displayable on my web page. So far my approach is the following :

  1. A three dimensional integer array in a C script is use to accumulate the image data. Dimensions are width, breadth and color (R, G and B).
  2. The array is written to a ppm-file.
  3. The next picture is accumulated and written and so on.
  4. With ffmpeg a script merges the ppm-files to a mp4-video.

  Basically this works, but of course faster would be nicer. I would appreciate proposals for fundamentally different approaches as well as help on the following details :

  • Is there a file format simple as ppm that uses the HEX code for colors instead of triplets ? This would reduce the size of my array as well a the number of write operations.
  • Do I loose much time if I print every single value to the file with an fprintf operation instead of accumulating lines into a string ? Or do compilers optimize this kind of sequences of writes ?

• avformat/hlsenc : fix hlsenc bug at windows system

  13 janvier 2017, par Steven Liu

  avformat/hlsenc : fix hlsenc bug at windows system
  when hlsenc use flag second_level_segment_index,
  
  second_level_segment_size and second_level_segment_duration,
  
  the rename is ok but the output filename always use the old filename
  
  so move the rename operation after the close the ts file and
  
  before open new segment
  Reported-by : Christian Johannesen <chrisjohannesen@gmail.com>
  
  Reviewed-by : Bodecs Bela <bodecsb@vivanet.hu>
  
  Signed-off-by : Steven Liu <lq@chinaffmpeg.org>
  

  • [DH] libavformat/hlsenc.c