Help, slow playback


#1

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?

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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.


#2

yes something is wrong its taking much too long.


#4

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.


#5

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.