[PLUG] Video transcoding framerate problem: ogg -> avi

Scott Garman sgarman at zenlinux.com
Mon Jan 9 17:30:18 UTC 2012


On 01/07/2012 12:56 AM, wes wrote:
> On Fri, Jan 6, 2012 at 10:47 PM, Scott Garman<sgarman at zenlinux.com>  wrote:
>
>> Hello,
>>
>> I'm going a bit crazy trying to do something that I think should be
>> quite simple.
>>
>> I'm creating some screencasts, using GTK RecordMyDesktop. It produces
>> Ogg Theora video files. I need to convert these to AVI files for later
>> processing.
>>
>> Using mencoder, I'm finding that the framerate and length of the
>> resulting video does not match the original by a long shot. A 10-minute
>> ogg video comes out as 7 minutes after transcoding. According to GTK
>> RecordMyDesktop, the framerate of the original should be 15fps.
>>
>> mencoder has two options for framerate. -fps specifies the framerate of
>> the original file, and -ofps specifies the framerate of the output file.
>> Setting either or both of these to 15 still does not resolve the issue.
>>
>> By trial and error I managed to create an output video of the expected
>> length by setting -fps to 6.28. But this only applies to that particular
>> video, and I have dozens more of different lengths to do the same to.
>>
>> I've also tried using ffmpeg to do the conversion. It gets the length of
>> the video correct but degrades the quality substantially, so I'd like to
>> see if I can get mencoder to work properly.
>>
>> Has anyone else encountered this before? I've gone down so many
>> dead-ends via Google now that my head is spinning.
>>
>> Thanks,
>>
>> Scott
>>
>
> My advice is to stick with ffmpeg, and play with the quality settings until
> you get acceptable results.

This turned out to be the best approach. All I needed to discover was 
the -sameq option to ffmpeg, which preserves the quality level of the 
original video.

Thanks for the replies,

Scott




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