Changes between Version 7 and Version 8 of Encode/VFX


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Timestamp:
Nov 7, 2012, 6:21:04 AM (7 years ago)
Author:
jakubk
Comment:

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  • Encode/VFX

    v7 v8  
    9292|| avc1 || yuvj422p || 2048x1152 || 146389 || 48 || 168M || H264, keyint = 48, CRF 7 ||
    9393|| avc1 || yuvj422p || 2048x1152 || 286524 || 48 || 328M || H264, keyint = 48, CRF 1 ||
     94
     95== Using the linux render farm
     96Most VFX shops would have a linux based render farm lying around somewhere, crunching up maya and nuke scripts and then next to it would most likely be a pile of old xserves running whatever apple OS X version would run on them and these would be used for generating clips. The ideas presented in this document are geared towards enabling the full use of a linux render farm in a movie making worflow. All of the above can be done has been done on linux  so the people in charge of the system running no longer have to stress about the fact that it is no longer possible to buy xserves. One thing that remains is how do make this parallel? It's nice to be able to send jobs to the farm scheduler and have it run them on any node without worrying about it, but it would be even better if we could encode the video sequence in parallel on many machines, each doing only a subset of the total frames, and then concatenating them into one final clip. The good news is that we can absolutely do that!
     97
     98FFmpeg can be told to encode only a subset of frames, or we could have the first job that generates our DPX source put them into different directories - whichever one is easier. After that, we can just run ffmpeg on a subset of the frames with the same parameters (but we must make sure we always use the same number of frames, because our movies must be of the same length) and them glue them together into one final clip. This is in theory possible with the default ffmpeg *concat* filter as [http://ffmpeg.org/faq.html#How-can-I-concatenate-video-files_003f described in this document] but I have found this to not work. Instead, a way around this is to use mencoder for the final concatenation of the clips. For the codec we would just use the "copy" keyword and pass it multiple inputs (in order) and then have it write out one output. The command for this is along the lines of:
     99{{{
     100mencoder -oac copy -ovc copy frames0001-0100.mov frames0101-0200.mov -o /tmp/concat.mov
     101}}}