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• Using lcov With FFmpeg/Libav

  21 novembre 2011, par Multimedia Mike — Programming, code coverage, ffmpeg, lcov, libav

  Last year, I delved into code coverage tools and their usage with FFmpeg. I learned about using GNU gcov, which is powerful but pretty raw about the details it provides to you. I wrote a script to help interpret its output and later found another script called gcovr to do the same, only much better.

  I later found another tool called lcov which is absolutely amazing for understanding code coverage of your software. I’ve been meaning to use it to further FATE test coverage for the multimedia projects.

  
  
  Click for larger image
  

  Basic Instructions
  Install the lcov tool, of course. In Ubuntu, 'apt-get install lcov' will do the trick.

  Build the project with code coverage support, i.e.,

  ./configure —enable-gpl —samples=/path/to/fate/samples \
   —extra-cflags="-fprofile-arcs -ftest-coverage" \
   —extra-ldflags="-fprofile-arcs -ftest-coverage"
  make
  

  Clear the coverage data :

  lcov —directory . —zerocounters
  

  Run the software (in this case, the FATE test suite) :

  make fate
  

  Let lcov work its magic :

  lcov —directory . —capture —output-file coverage.info
  mkdir html-output
  genhtml -o html-output coverage.info
  

  At this point, you can aim your web browser at html-output/index.html to learn everything you could possibly want to know about code coverage of the test suite. You can sort various columns in order to see which modules have the least code coverage. You can drill into individual source files and see highlighted markup demonstrating which lines have been executed.

  As you can see from the screenshot above, FFmpeg / Libav are not anywhere close to full coverage. But lcov provides an exquisite roadmap.

• FFmpeg command help and pointers for documentation

  27 novembre 2011, par mahi

  I was working with FFmpeg for one of my android project. So far, I have been able to successfully able to compile FFmpeg for ARM. Now my approach is to write a JNI interface for playing videos using FFmpeg.

  I tried executing the command ./ffmpeg --help to see the options available with FFmpeg, and so far I am only able to understand that the input filename can be provided with -i fileName option.

  I have been searching for online tutorials / blogs for FFmpeg commands, and how to play a video / RTMP stream, but couldn't find a suitable link.

  I'd like to know the following :

  1. What is the command to play a video using FFMpeg ?
  2. What is the command to play a local file using FFMpeg
  3. What is the command to play a RTMP stream using FFMpeg
  4. Java / C sample code to play video using FFMpeg
  5. Is it possible to extract some piece of code from ffplay.c and write a custom code ?

  Any help with the above and / or any pointers to relevant links is highly appreciated.

  Thanks.

• Convert wmv to mp4 with ffmpeg failing

  10 janvier 2012, par Morph

  I've seen quite a few posts on this, but I can't piece together whether I am doing things right, wrong, or need to download more stuff. I am converting from wmv to mp4 without complaints, but then when I go to play it on the browser window (HTML5) the player just turns grey and blanks out the controls.

  Installing ffmpeg I do

  ./configure --disable-yasm ; make ; make install

  Unless I include the disable yasm it wont go any further. Then I do

  ffmpeg -i myvideo.wmv myvideo.mp4

  All good so far. In my html source I have :

    <video width="320" height="240" controls="controls">
  
    <source src="myvideo.mp4" type="&#39;video/mp4;" codecs="avc1.42E01E, mp4a.40.2"></source>
  
    Your browser does not support the video tag.
  
    </video>

  I am playing this in Chrome 15 and ffmpeg -v is

  ffmpeg version 0.8.6, Copyright (c) 2000-2011 the FFmpeg developers
  
  built on Dec  1 2011 15:42:06 with gcc 4.1.2 20080704 (Red Hat 4.1.2-51)
  
  configuration: --disable-yasm
  
  libavutil    51.  9. 1 / 51.  9. 1
  
  libavcodec   53.  7. 0 / 53.  7. 0
  
  libavformat  53.  4. 0 / 53.  4. 0
  
  libavdevice  53.  1. 1 / 53.  1. 1
  
  libavfilter   2. 23. 0 /  2. 23. 0
  
  libswscale    2.  0. 0 /  2.  0. 0

  So I get the HTML5, click on it to play the movie but then the control bar greys out, leaving the play button, but then the play button cannot be clicked and nothing plays.

  Is there something wrong with what I have done above ? Do I need to download some separate mp4 driver and compile it ? I see people referring to h.264 but I thoughts ffmpeg had that already included...