[FFmpeg-user] Proper way to reverse PAL Speed up?

Bernd Butscheidt bbutscheidt at yahoo.de
Sun Feb 3 18:01:27 CET 2013

----- Original Message -----
> From: Carl Eugen Hoyos <cehoyos at ag.or.at>
> To: ffmpeg-user at ffmpeg.org
> Cc: 
> Sent: Sunday, February 3, 2013 3:31 PM
> Subject: Re: [FFmpeg-user] Proper way to reverse PAL Speed up?
> Bernd Butscheidt <bbutscheidt <at> yahoo.de> writes:
>>  >Alternatively, please provide a sample.
>>  I uploaded a cut version of the source file - the 
>>  original was 200MB. I choose this one although it 
>>  is no film material
> So you intentionally did not upload a sample that allows 
> to reproduce the original task - sorry, but I did not 
> think of this possibility.

Sorry, now I've lost you. The sample I provided is from the same source and the same task is done with it supplying the same behaviour. The only reason I cut the original test sample was due to the limitation of datafilehost.com which is 100 MB. 

The resulting videos are 23.976 fps with proper sound - so mainly it works. Still I wonder why I have to add an offset to the audio of about 250ms. Both results, without offset and with offset, I uploaded as well. 

Because I have to find the proper offset by trial and error, I feel uncomfortable and search for a logical reason where it derives from. 

If I missed something, please return to me with the things I need to supply additionally. From my point of view, everything I wanted to show can be seen and heard with the uploaded samples?!

>...it of course drops half of the 
>input frames but that simply may be what you want) but 
>given that I don't understand what you want to achieve, 
>it is difficult for me to make suggestion

The source is a German TV Recording (ZDF HD) broadcast in 50fps. I indeed want to speed down to double ntsc-frame rate (asetpts, setpts) and drop every second frame (-r 24000/1001) to achieve true ntsc film rate. The same command line also works with 25fps input, but no frames are dropped - and concerning the video-audio offset, it behaves the same to my experience.

If it is of help I can record a small sample of a SD-station broadcasting in 25fps and apply the commands.

Kind regards
Bernd B.

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