[FFmpeg-user] shuffleframes -- unexpected results

[Mark Filipak (ffmpeg)]

On 2021-02-21 21:39, pdr0 wrote:
> Mark Filipak (ffmpeg) wrote
>> I've run some test cases for the shuffleframes filter. I've documented
>> shuffleframes via my
>> preferred documentation format (below). In the course of my testing, I
>> found 2 cases (marked "*****
>> Expected", below) that produced unexpected results, to wit: If the 1st
>> frame is discarded, the
>> entire input is discarded, even if the 1st discard is followed by frames
>> that are supposed to be
>> retained.
>>
>>                 -1 1    ...Blocks the pipeline (discards all frames). *****
>> Expected 1 3 5 7 ..
>>                 -1 1 2   ...Blocks the pipeline (discards all frames).
>> ***** Expected 1 2 4 5 7 8 ..
> 
> These 2 cases produce the expected result for me
> 
> If the "entire input is discarded" - do you mean you get no output file at
> all ?

No output file at all. The transcodes complete (they don't hang awaiting end-of-stream) but since 
the pipeline contains no frames, the encoder makes nothing and ffmpeg makes no files.

> Post more info, including the console log

First, for context, the scripts:
ffmpeg -i 0.mkv -vf shuffleframes="-1" -dn "\-1.mkv"
ffmpeg -i 0.mkv -vf shuffleframes="-1 1" -dn "\-1 1.mkv"
ffmpeg -i 0.mkv -vf shuffleframes="-1 1 2" -dn "\-1 1 2.mkv"

I had to escape the '-' in the filenames in order to avoid this complaint:
"Unrecognized option '1 1 2.mkv'.
"Error splitting the argument list: Option not found"

Perhaps it would be expeditious if you showed me your command line that works, eh?