Help needed with ffmpeg/ffplay and select

[Selur]

I want to look at 5% of my clip using 5 second chunks.

So looking at a clip with 125906 frames and a frame rate of 25fps I calculated:

• chunkSizeInFrames = outputFrameRate * "selection length in seconds" = 25 * 5 = 125
  the length of the chunks I want to look at
• maxChunkCount = outputFrameCount / chunkSizeInFrames = 125906/125 = 1007
  the maximal number of chunks that could be created from my source
• neededChunkCount = maxChunkCount * percent / 100 = 1007*5/100 = 50
  the number of chunks I want to look at
• distanceBetweenChunks = outputFrameCount / neededChunkCount = 125906/50 = 2518
  the distance between the starting points of the chunks

So what I want is to use the first 125 frames of every 2518 frames, thus I thought my call should look like this:

ffplay -i "path to file" -vf "select='lt(mod(n\, 2518),125)',setpts='N/(25*TB)'" -an

Problem is, this still doesn't seem to be correct, since the chunks appear to be too small.

-> Does anybody know how to 'fix' this?

Cu Selur

[Selur]

okay, seems like when I use ffmpeg instead of ffplay it works like it should.

-> Anybody got an idea how to also do this with mencoder?

[Selur]

=> only way seems to be the use of previously created edl files