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• undefined reference to `x264_encoder_open_125'

  18 juin 2013, par Vishal

  While installing ffmpeg on Ubuntu 12.04

  I am getting following error

  libavcodec/libavcodec.a(libx264.o): In function `X264_init':
  
  /root/ffmpeg/libavcodec/libx264.c:492: undefined reference to `x264_encoder_open_125'
  
  collect2: ld returned 1 exit status
  
  make: *** [ffmpeg_g] Error 1

  I am following the instructions given at
  http://ffmpeg.org/trac/ffmpeg/wiki/UbuntuCompilationGuide

  Do anyone have idea about this error ?

• ffmpeg encoding slowly, not using much CPU

  30 juin 2012, par eblume

  I am using the latest (as of this post) version of ffmpeg on OS X as installed via homebrew (an OS X 3rd-party package manager with a good reputation.) I am trying to encode video that was recorded using Fraps on another machine to reduce the file size while preserving as much quality as is reasonably possible.

  Fraps records video in a .avi container and I believe does absolutely no encoding - instead, it's just a stream of image files. The resulting files are often enormous, obviously. I want to set up a cron job that finds recorded files and encodes them to H.264 with some sort of audio codec (I'm currently using libmp3lame but will revisit it when I get video working right - will probably switch to a lossless audio codec.)

  My problem is that while encoding seems to be working exactly how I want it - very few compression artifacts but about 5% of the original size - the encoding is taking forever. I'm averaging about 1.5 encoded frames per second, and these are 2-3 hours of 30FPS video. On top of that, my CPU is never fully utilized. On my dual-core CPU I am getting a median usage of about 40% of one core, with occasional peaks of 140% to 160%.

  So the question is : How can I speed up encoding ? I'm sure there's got to be some options I'm missing out on.

  Here's the command I use :

  ffmpeg -i INFILE -c copy -c:a libmp3lame -ar 44100 -q:a 5 \
  
                -threads 0 -c:v libx264 OUTFILE

  Thanks !

  EDIT : Actually, it looks like this command isn't compressing that well either - I'll do some digging but it seems that this might be being too generous with the bitrate for H.264. At first I was getting around 2Mb/s but it's gone up to almost 20Mb/s - looks like I'm basically not compressing at all.

• Podcast Producer 2 tip - running xgrid jobs as logged in user

  19 octobre 2009

  So I’ve been playing with an interesting "feature" in PCP2 - the "chapterize" command generates different results when it can talk to the window server versus when it can’t. In my case, it generates much better results in the case of the former.

  "But," you say, "my PCP2 xgrid jobs can’t talk to the window server !"

  Very true. However, you can change the user that PCP2 uses to submit Xgrid jobs, and Xgrid will run the job with that user’s permissions if everyone is single signon’d to the same kerberos domain.

  So, now we’ve got PCP2 jobs running as a real user. Next, log into the GUI as that user.

  Now, when PCP2 workflows run, they’ll be able to talk to the window server, and at least in the case of "chapterize," use what appears to be the "Good" code path. Faster, more accurate, more delightful.