[vtk-developers] vtkFFMPEGWriter - bitrate and bitrate tolerance

[Nicolas Rannou]

something like that might be enough:
GIT repository: git at github.com:NicolasRannou/VTK.git

I just added 2 variables BitRate and BitRateTolerance in the  
vtkFFMPEGWriter.cxx.
They are initialized to 0.

If they they are not modified( i.e. equal 0), the vtkFFMPEGWriter  
would work exactly in the same way as before.
If we modifify one of the value, we would use the modified values:

c->bit_rate = BitRate  rather than
c->bit_rate = preset value

and

c->bit_rate_tolerance = BitRateTolerance  rather than
c->bit_rate_tolerance = c->bit_rate/this->FrameRate;

Let me know if it is enough.
It worked fine for me but more modification might have to be done (not  
sure since I am not a FFMPEG expert).

     Nicolas

On Jul 29, 2010, at 4:41 PM, Dave Partyka wrote:

> In the past there were no versions of FFMPEG (until just recently)  
> other than svn revisions. So we just picked an arbitrary revision  
> that worked on all of our platforms and stuck with it. Also, we use  
> one of the most basic and mature codecs (mjpeg) which I don't think  
> has changed much? Anyway, keep us posted.
>
> On Thu, Jul 29, 2010 at 4:37 PM, Nicolas Rannou <Nicolas_Rannou at hms.harvard.edu 
> > wrote:
> I think that if the ancient FFMPEG is working with the current VTK  
> git master it should still work after.
> I'm currently using the FFMPEG deb package provided with ubuntu 10.04.
>
> I'll fork the VTK git master, commit the changes and let you know as  
> soon as it is done then we can give it a try with Paraview.
>
> Is there any reason about using the ancient FFMPEG in Paraview?
>
>     Nicolas
>
> On Jul 29, 2010, at 3:38 PM, Dave Partyka wrote:
>
>> I don't have any objections but would like to know if that change  
>> is compatible with the ancient FFMPEG we typically release ParaView  
>> with.
>>
>> http://www.vtk.org/files/support/ffmpeg_source.tar.gz
>>
>>
>> On Thu, Jul 29, 2010 at 3:21 PM, Nicolas Rannou <nicolas_rannou at hms.harvard.edu 
>> > wrote:
>> Hi all,
>>
>> We are experimenting issues regarding the usage of  
>> vtkFFMPEGWriter.cxx.
>> It occurs at least on Mac and Ubuntu 10.04.
>> You can reproduce the error turning VTK_USE_FFMPEG ON and running the
>> associated test. (ctest -R FFMPEG)
>>
>> ERROR:
>> [mjpeg @ 0x2db2f30]bitrate tolerance too small for bitrate
>> Generic Warning: In /home/nr52/GITROOT/VTK/IO/vtkFFMPEGWriter.cxx,  
>> line 197
>> Could not open codec.
>>
>> The problem is located at /VTK/IO/vtkFFMPEGWriter.cxx:179, where  
>> the bit_rate_tolerance is defined as:
>> c->bit_rate_tolerance = c->bit_rate/this->FrameRate;
>>
>> Then, this error ("bitrate tolerance too small for bit-rate") can  
>> easily be solved decreasing the FrameRate.
>>
>> Moreover, there is no convenient method to set the bit-rate.
>> So far, can only choose between 3 predefined bit-rates, which is  
>> quite restrictive.
>>
>> So here is my question: Is there any reason for not creating  
>> variables BitRate and BitRateTolerance?
>> If there is no objection, I can take care of it.
>>
>> Thanks
>>
>>
>>    Nicolas
>>
>>
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