Help, slow playback


Hello everyone, I downloaded the latest version of natron and I started to play with it. But I realize that with just a “read” with a video of 1280x720 in h264, connected to a “view” and I give to the play, this will jerks to a reproduction of between 3 to 9 fps, as the line advances Of the time turns green and if I return to the beginning of the line that this green already reproduces correctly. But I find it strange that in my team, “the burden” is so slow. My computer is an i7, Nvidia GT750M - driver 375.39, 8 GB Ram and as a Neon operating system (ubuntu 16.04).

Can anyone tell me if this is so or should I configure something in preferences?


As my computer has 2 gpu cards, an intel HD4000 and the Nvidia GT750M. I have done some tests with an HD video and only let him reproduce 200 frames, to know the performance of the 2 GPUs

With HD4000: It takes 1 minute and 14 seconds to generate the cache and start playing correctly.
With GT750M: It takes 1 minute and 25 seconds to generate the cache and start playing correctly.

As you can see something wrong works, it can not be that a dedicated GPU card, it takes longer to perform the same work as an integrated one. When other programs show the difference.


yes something is wrong its taking much too long.


Reading a video has nothing to do with the GPU, it’s a plain CPU job.
There can be many reasons why the playback of a video is slow:

  • The codec fails to decode properly and needs many retries
  • Natron has too many threads active resulting in threads blocking out each others. This is something that we worked on in Natron 3, but unfortunately on Natron 2 if you have a computer with many cores, you may want to tweak the setting “Number of parallel renders” and set it to a reasonable amount of threads (say 8).
    Note that in Natron 2, it performs multi-threading over frames, i.e: multiple renders at different frames occur simultaneously. For reading a video this often results in degraded performances.
    Natron will generally work better with image sequences.

Also bear in mind that Natron is not just VLC: it converts the input image to 32 bit floating point and performs high quality color-space conversion on it, because the use-case of Natron is to composite and modify an image whilst retaining a good quality.

Natron will work better (with respect to the multi-threading and all) if you apply more complicated graphs rather than a single (Reader–>Viewer) where in that case, of course a simple media player will do a better job.


Thanks MrKepzie, I put the number of parallel renders in 8 and now in my small test of 200 ftp it only takes about 35 seconds to load the cache.
Before reading your answer, I had downloaded the windows version and using wine, I ran it and performed the same test, and on wine Natron it took me to load the cache about 35 seconds.

From what I understand in my computer the linux version, did not recognize threads well automatically, as they come by default.