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• libx264 in Visual Studios 2010 - Memory error in Release Build

  21 décembre 2011, par DeusAduro

  I am building an application and using the x264 library as an encoder. I have built the library for my windows system using MSys/MingW. The library works fine under debug build (note both debug and release builds are using the default VS2010 settings). However, under release an access violation error is thrown at the first call to the x264 library, specifically :

    Unhandled exception at 0x00905a4d in StreamTest.exe:
  
    0xC0000005: Access violation.

  The error is thrown at this line :

  x264_param_default_preset((params), "veryfast", "zerolatency");

  While I was figuring out how to compile the library I came across a lot of talk about memory alignment in Windows/Visual Studios and how it wasn't particularly compatible with the alignment expected by x264. For example when compiling in MSys I had to enable —enable-memalign-hack. I am wondering if the source of this error might stem from a memory alignment issue which only manifests itself through some setting in my release build. Unfortunately I know almost nothing about the specifics and so have come here.

  Can anyone give me some more information regarding the memory alignment issues and any Visual Studio settings which might cause this ? Any other tips/pointers to fix this issue are very welcome.

  Thanks.

  Edit

  From answer below :

  1. From the linked SO question I get the impression he added "build with debugger info" to the OpenCV build ? Since I'm building the x264 library through MSys with G++ I'm not sure I can do this. I have checked the build settings for my project, and under both release and debug it has debugger info. Not sure if I missed something in that post, please let me know.

  2. I tried the application verifier. It seems that x264 is trying to execute code from non-executable memory as per the App verifier output :

     VERIFIER STOP 0000000000000650: pid 0x1B18: 

     Attempt to execute code in non-executable memory (first chance).

     0000000000905A4D : Address being accessed.
     
     0000000000905A4D : Code performing invalid access.
     
     000000000021EA90 : Exception record. Use .exr to display it.
     
     000000000021E5A0 : Context record. Use .cxr to display it.

  Anything to be gathered from this output ?

  Thanks again.

• FFMPEG reports invalid video resolution, video headers container seem to be different from actual frames !

  20 décembre 2011, par Emiliano

  Quick question, i have a movie, which was cut and rendered with Sony Vegas from its original format to a .wmv file. Here comes the tricky part, movie when played, either with VLC or WMP, has a resolution of 656x480 ... BUT when i run a ffmpeg -i on it, it says it has a resolution of 600x480 ....

  I took the time of actually capturing a frame and croping it with photoshop and its 656 and not 600 like ffmpeg its reporting, why would this could be happening ? How could i fix the headers resolution ? Would that have any impact on video re-rendering ? As i said, VLC and WMP seems not to care about the incorrect headers and are playing it right, BUT, jwplayer seems to be using the header information, which i don't blame him, its correct to do that, but why the video headers could be wrong ?

  ffmpeg -i trailer.wmv

  Input #0, asf, from 'trailer.wmv' :
  Duration : 00:01:04.93, start : 3.000000, bitrate : 2144 kb/s
  Stream #0.0 : Audio : wmav2, 44100 Hz, mono, 32 kb/s
  Stream #0.1 : Video : wmv3, yuv420p, 600x480 [PAR 59:54 DAR 295:216], 2065 kb/
  s, 25.00 tb(r)

  And yeah, the PAR/DAR parameters are also wrong, but honestly, i don't understand that technical shit, usually watch video and make sure it look good, any feedback would be appreciated :P

  Is there a way to change the container information with ffmpeg so applications that actually do use the container information don't render video incorrectly ?

• Batch statement to convert mp3 to aac

  20 décembre 2011, par Soham Dasgupta

  My question is straight forward. I have tow commands to convert a single mp3 file to aac in tow pass. Here are the commands -

  ffmpeg -i input.mp3 -f wav - | neroAacEnc -ignorelength -q 0.5 -if - -of output.m4a
  
  
  
  ffmpeg -i output.m4a -y -vn -acodec libvo_aacenc -ab 128k -ar 48000 -ac 2 final.aac

  Please guide me to some script where I'll be able to convert a folder full to mp3 files in one shot. Suppose if its a VBScript then would it ask for the folders where mp3 are kept.

  Also a question about libvo_aacenc codec, is it the best codec to convert to aac if not then what codec should I use for the second pass for converting m4a to aac with highest compression but good quality. The above settings does not produce too good compression. Please help. Am very new to audio encoding.