Blender Sequencer speed is Extremely slow I have a video (720p) that is 37 minutes long, with a bitrate of ~3000kb/s.

This video is a game recording, so 37 minutes worth of this footage was written in 37 minutes, while other extremely CPU, GPU and hard-drive intensive operations were occurring.

If the recording program can record and output at the same rate as is being played, I don't understand why rendering with blender at the same exact settings, same codec, same container type, same bitrate and size, the only difference being that I removed about 4 seconds from the beginning, is going to take 5.3 hours to render.

I've disabled every feature under user preferences that are said to increase performance, I disabled rendering of the 3D scene (which is empty anyways). I set the sequencer memory cashe limit higher, I've increased the number of prefetch frame which is supposed to help with multicore rendering.

What else can I do to make the rendering faster? I've used blender for years for 3D, and I'm getting into recording videos for YouTube, all the good programs for video editing are very expensive. But those programs can render 37 minute videos in 10-20 minutes, not 5.3 hours. I don't understand why it's so slow, it's so slow to the point it's unusable.

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@user277143: My guess: try increasing the cache of blender itself too (alongside the Sequencer's cache). Also, having meshes in the scene will cause them to be reloaded for every frame. That can cause problems. So, go to the 3D-view and delete everything. Also, off topic, check the resolution multiplier in the render settings. I have screwed up many sequence renders by having it at 50%.

I have already done the cache of Blender as well. I already have nothing in the 3D scene, and I even have that entire render layer disabled in the outliner.

@gandalf3: Related:


How to make VSE render faster?
VSE suddenly slow like hell
Poor performance with h.264 VSE
How to speed up Blender Video Sequence Editor rendering?
Is the VSE multi-threaded?


I've seen all of those, none of them provide any help that has altered the result. Those issues were due to bugs, or a settings issue. In the past I've been able to render at around 50-60 outputted frames per second, so rendering a 30 minute video in 15-18 minutes. Only in the last 3 weeks has this started to take this long, so there is a way somehow to speed it up, and I haven't touched any settings on the program.
Keep UI


render with "Keep UI" option in the Render properties panel under Display
(Just don't let blender display the rendering process in any window.) That was a noticeable speed up for me.


Multicore rendering  


use one of the available scripts for multi-core rendering. Basically a script that opens as many instances of Blender as you have cpu cores or as many as you specify.
(Blender use for VSE render only one core of CPU by default. So even with a two core processor you get only half the render time. If you have an 8core CPU it would be great speed boost for you.)


Parallel Render - Addon, simple to use, but it generates separate movie files - one for each blender instance (that runs on each core separately).
After download, installation, enable ... you run this script with SPACEBAR search, type "parallel ..."

￼

video_editor_render_script - A python script whit it you need to arrange a few things first, but then it's a ONE-CLICK option with one animation file.
(Namely -download also ffmpeg and specify paths to blender and to ffmpeg in the script. Just follow instructions. In general it also generates separate files for each core first, but than use ffmpeg to merge them in one file.)