[FFmpeg-user] Zoompan filter, frame counts seem to start from 2 and 1, not 0 -- expected behaviour?

Gyan Doshi gyandoshi at gmail.com
Sat Jun 2 13:25:20 EEST 2018

On 02-06-2018 02:39 PM, Jim DeLaHunt wrote:
> On 2018-06-02 01:22, Gyan Doshi wrote:
>> This isn't related to the zoompan filter. If you ask ffmpeg to not 
>> compress the log messages by setting the repeat flag `-v +repeat`, 
>> you'll see that the crop filter processes the first frame twice.

Sorry. This is due to the crop filter evaluating x twice each frame, 
since x can refer to the y expr and the first eval of x may have failed.

> But even without the *crop* filter, the *zoompan* filter appears to be 
> starting its *in* and *on* frame counts at 3 and 2:

That should be "2 and 1"

This change occurred when zoompan switched to activate in 


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