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• Taking submissions for encoder comparison

  8 mai 2010, par Dark Shikari — Uncategorized

  With VP8 supposedly going to come out in about 2 weeks, it’s time to get a rough idea as to the visual state of the art in terms of encoders. Accordingly, I’m doing a small visual codec comparison in which we will take a few dozen encoders, encode a single test clip, and perform score-based visual tests on real humans using a blind test. There will be no PSNR or SSIM results posted.

  See the doom9 thread for more information and feel free to submit streams for your own encoders. I’m particularly interested in some newer proprietary encoders for which I wouldn’t be able to get the software for due to NDAs or similar (such as VP8, Sony Blu-code, etc) — but for which I would be able to get a dump of the decoded output.

• snow_dwt : Don’t try and free members of non-existent arrays

  15 décembre 2014, par Derek Buitenhuis

  snow_dwt : Don’t try and free members of non-existent arrays
  If allocation fails earlier on, and the next frame is processed,
  
  the slice buffer could be left in a state where line and data_stack
  
  have already been freed, or are otherwise null pointers.
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavcodec/snow_dwt.c

• Using gcovr with FFmpeg

  6 septembre 2010, par Multimedia Mike — FATE Server

  When I started investigating code coverage tools to analyze FFmpeg, I knew there had to be an easier way to do what I was trying to do (obtain code coverage statistics on a macro level for the entire project). I was hoping there was a way to ask the GNU gcov tool to do this directly. John K informed me in the comments of a tool called gcovr. Like my tool from the previous post, gcovr is a Python script that aggregates data collected by gcov. gcovr proves to be a little more competent than my tool.

  Results
  Here is the spreadsheet of results, reflecting FATE code coverage as of this writing. All FFmpeg source files are on the same sheet this time, including header files, sorted by percent covered (ascending), then total lines (descending).

  Methodology
  I wasn’t easily able to work with the default output from the gcovr tool. So I modified it into a tool called gcovr-csv which creates data that spreadsheets can digest more easily.

  • Build FFmpeg using the '-fprofile-arcs -ftest-coverage' in both the extra cflags and extra ldflags configuration options
  • 'make'
  • 'make fate'
  • From build directory : 'gcovr-csv > output.csv'
  • Massage the data a bit, deleting information about system header files (assuming you don’t care how much of /usr/include/stdlib.h is covered — 66%, BTW)

  Leftovers
  I became aware of some spreadsheet limitations thanks to this tool :

  1. OpenOffice can’t process percent values correctly– it imports the percent data from the CSV file but sorts it alphabetically rather than numerically.
  2. Google Spreadsheet expects CSV to really be comma-delimited– forget about any other delimiters. Also, line length is an issue which is why I needed my tool to omit the uncovered ine number ranges, which it does in its default state.