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• How to benchmark the decoding of the frame by ffmpeg ?

  13 juin 2018, par Anny G

  [ What I have done ]

  I am trying to measure a performance of different ffmpeg decoders by

  • timing how long the call to function avcodec_decode_video2(..) takes in ffmpeg.c and running ffmpeg binary the following way

  ~/bin/ffmpeg -benchmark_all -loglevel debug -threads 0 -i ~/Documents/video-input.h264 -c:v libx265 -x265-params crf=25 video-output.hevc

  • and by timing how long the same function takes in ffplay.c and running the ffplay binary the following way

  ~/bin/ffplay ~/Documents/video-input.h264

  In my understanding the average time for the call to that function should be the same whether I am converting the video or playing it, because I am only measuring how long it takes to decode the frame for that video. Is this a wrong way of doing it ? Please let me know if I am incorrect. The results I am getting are strange to me - the call to the aforementioned function takes twice as much in ffmpeg binary compared to ffplay binary. I have tried to run ffmpeg binary with -threads 0 and without it, but the results are still the same(twice as long as ffplay). Could it be because ffplay binary simply utilizes more threads ? When I try it with -threads 1, ffmpeg takes about 10 times as long as ffplay (which makes sense to me since before it was using several threads and now it is only using 1)

  Before I ask my question, I want you to know that I am a beginner in video processing and video encoding/decoding processes.

  [My question]

  I am wondering what would be an accurate way to measure how long it takes to decode a frame (using 1 thread) ? Should I simply measure only how long it takes to call avcodec_decode_video2(..) function using the ffmpeg binary, and not the ffplay binary ? Would the results be more accurate that way ?
  I also tried to enable -benchmark_all -loglevel debug options, but it seems like the following message bench:    64537 decode_video 0.0 is not very helpful if 0.0 is supposed to mean time. (Not sure what the other number means).

• Can't get ffmpeg to stream webcam [on hold]

  29 novembre 2017, par joey

  I have a rapsberry with ffmpeg installed and a microsoft hd3000 cam installed
  I run the following command :
  ffserver -f /etc/ffserver.conf & ffmpeg -framerate 21 -re -f video4linux2 -i /dev/video0 -f alsa -i sysdefault:CARD=HD3000 http://localhost:8090/feed1.ffm

  and i get the following :

  /etc/ffserver.conf:164: Setting default value for video bit rate tolerance = 16000. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:164: Setting default value for video rate control equation = tex^qComp. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:164: Setting default value for video max rate = 6229744. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:219: Setting default value for audio sample rate = 22050. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:219: Setting default value for audio channel count = 1. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:219: Setting default value for video bit rate tolerance = 64000. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:219: Setting default value for video rate control equation = tex^qComp. Use NoDefaults to disable it.
  
  /etc/ffserver.conf:219: Setting default value for video max rate = 6369328. Use NoDefaults to disable it.
  
  bind(port 8090): Address already in use
  
  Wed Nov 29 13:17:49 2017 Could not start server
  
  [video4linux2,v4l2 @ 0x1a35630] The driver changed the time per frame from 1/21 to 1/10
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 12116.079136, bitrate: 147456 kb/s
  
      Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 1280x720, 147456 kb/s, 10 fps, 10 tbr, 1000k tbn, 1000k tbc
  
  Guessed Channel Layout for Input Stream #1.0 : stereo
  
  Input #1, alsa, from 'sysdefault:CARD=HD3000':
  
    Duration: N/A, start: 1511961469.424072, bitrate: 1536 kb/s
  
      Stream #1:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  [tcp @ 0x1a44160] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  Wed Nov 29 13:17:49 2017 127.0.0.1 - - [GET] "/feed1.ffm HTTP/1.1" 200 4175
  
  [tcp @ 0x1a63ca0] Connection to tcp://localhost:8090 failed (Connection refused), trying next address
  
  [mpeg1video @ 0x1a6ecb0] bitrate tolerance 21333 too small for bitrate 64000, overriding
  
  [mpeg1video @ 0x1a6ecb0] MPEG-1/2 does not support 3/1 fps
  
  Stream mapping:
  
    Stream #1:0 -> #0:0 (pcm_s16le (native) -> mp2 (native))
  
    Stream #0:0 -> #0:1 (rawvideo (native) -> mpeg1video (native))
  
    Stream #1:0 -> #0:2 (pcm_s16le (native) -> wmav2 (native))
  
    Stream #0:0 -> #0:3 (rawvideo (native) -> msmpeg4v3 (msmpeg4))
  
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height
  
  Wed Nov 29 13:17:49 2017 127.0.0.1 - - [POST] "/feed1.ffm HTTP/1.1" 200 0
  
  [2]+  Exit 1                  ffserver -f /etc/ffserver.conf

  I use the default /etc/ffserver.conf.
  I can’t seem to figur out what is the problem.

• Run 2 exec command in for loop with time interval of 30 seconds using TCL and FFMPEG

  29 novembre 2017, par M. D. P

  i want to Run 2 exec command in for loop with time interval of 30 seconds using TCL and FFMPEG

  my exec command for image is :

  exec ffmpeg -f dshow -benchmark -i video="Integrated Webcam" -s 1280x720 c:/test/sample_image%d.jpg

  my exec command for video is :

  exec ffmpeg -f dshow -benchmark -i video="Integrated Webcam" -s 1280x720 c:/test/sample_video%d.avi

  i want my code to be like this :

  proc a {} { 
  
  
  
  set a 1
  
  
  
  while {$a < 10} {
  
  
  
  after 3000
  
  
  
  exec ffmpeg -f dshow -benchmark -i "video=Integrated Webcam" -s 1280x720 c:/test/sample_image.avi
  
  
  
  after 3000
  
  
  
  exec ffmpeg -f dshow -t 00:00:30 -benchmark -i "video=Integrated Webcam" -s 1280x720 c:/test/sample_video.avi
  
  
  
  incr a
  
  
  
  }
  
  
  
  }
  
  a

  problem here is, after completion of first exec command, it stops its execution. that is it captures the image and stops its execution.

  I also want that this process of capturing image and video should work in loop (while or foreach).

  i have my present working code which execute only one exec command, that to only one. so i want this two exec command to run after one another in loop.

  error report for above program :

  % source c:/other/a/d.tcl
  
  
  
  ffmpeg version N-89212-ga60b2425c3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 7.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  
    libavutil      56.  2.100 / 56.  2.100
  
    libavcodec     58.  3.105 / 58.  3.105
  
    libavformat    58.  2.102 / 58.  2.102
  
    libavdevice    58.  0.100 / 58.  0.100
  
    libavfilter     7.  2.102 /  7.  2.102
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  Input #0, dshow, from 'video=Logitech HD Webcam C525':
  
    Duration: N/A, start: 90055.057000, bitrate: N/A
  
      Stream #0:0: Video: rawvideo, bgr24, 1280x720, 30 fps, 30 tbr, 10000k tbn, 10000k tbc
  
  File 'c:/test/sample_20171128_111245.jpg' already exists. Overwrite ? [y/N] [dshow @ 052d4ac0] real-time buffer [Logitech HD Webcam C525] [video input] too full or near too full (181% of size: 3041280 [rtbufsize parameter])! frame dropped!
  
      Last message repeated 886 times
  
  Not overwriting - exiting
  
  bench: maxrss=50856kB
  
  [dshow @ 052d4ac0] real-time buffer [Logitech HD Webcam C525] [video input] too full or near too full (181% of size: 3041280 [rtbufsize parameter])! frame dropped!
  
      Last message repeated 1 times
  
  %

  please provide me the code as answer which will work for above problem.