Author Topic: Version 2.7.3 (64bit) on Win7: very slow playback of 60fps x264 HD videos  (Read 688 times)

MoriMoriMori

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Hi, everybody.

When I try to open 4k 60fps 16:9 (60Mbit/s bitrate) videos created by GoPro Hero 7 Black in Avidemux 2.7.3 64bit (Win7 64bit, 32GB of RAM, Intel i5-6600k 4-cores CPU), they are played back at 1/2 - 1/3 of their actual speed, for some reason.

I have hardware acceleration enabled in the program (via DXVA2), and the same videos are played back fine by Mplayer 64bit I have installed here as well, still stressing out my system pretty bad, taking up to 70% of CPU at times. When I try to watch it in Avidemux, I only see around of 35% of CPU capacity utilized by it, so it may have something to do with the program not using multi-threading efficiently enough (I have the setting set to "Auto-detect", but I've tried setting it to 4-8 already, for no avail).

When I try to edit this video (though it's painfully inconvenient, as UI lags severely and it's hard to navigate through video and do cutting) and re-encode it to final piece, I can view it in Mplayer without a problem (so it doesn't affect encoding, only decoding).

First I thought it may be because Avidemux is not able to handle H265 codec (GoPro uses it by default). But it still the same even after I re-encoded a video to H264 (still keeping 60fps framerate). It also doesn't have issues with 30fps 60Mbit/s videos.

So, apparently Avidemux just can't handle decoding of 60fps HD videos properly? Is this a known issue? Any solution so far?
« Last Edit: September 15, 2019, 06:07:59 PM by MoriMoriMori »

eumagga0x2a

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Re: Version 2.7.3 (64bit) on Win7: very slow playback of 60fps x264 HD videos
« Reply #1 on: September 15, 2019, 07:33:49 PM »
When I try to open 4k 60fps 16:9 (60Mbit/s bitrate) videos created by GoPro Hero 7 Black in Avidemux 2.7.3 64bit

An obligatory question: why not the latest release (or, even better, the latest nightly)?

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(Win7 64bit, 32GB of RAM, Intel i5-6600k 4-cores CPU)

I have hardware acceleration enabled in the program (via DXVA2),

DXVA2 decoding didn't work prior to 2.7.4 on Windows 7, fixed in 2.7.4 (DXVA2 display worked and should be used in any case).

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First I thought it may be because Avidemux is not able to handle H265 codec

From 2.7.4 on, 8bit HEVC is supported on Intel GPU with very recent driver versions (it was crashing due to driver bugs before). 10bit HEVC is unsupported on Intel, but the blacklist can be disabled in Avidemux preferences for testing purposes (again, please use the current version).

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So, apparently Avidemux just can't handle decoding of 60fps HD videos properly?

Maybe even working DXVA2 decoding with DXVA2 display enabled won't be enough for 60fps at 4k because we can't do a full HW accel with DVXA2 yet. We have to download decoded picture data to the main memory and reupload it back to the graphics card for display. At least my MBP can't do it with 4k HEVC in real time (but it is only slightly below RT).

MoriMoriMori

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Re: Version 2.7.3 (64bit) on Win7: very slow playback of 60fps x264 HD videos
« Reply #2 on: September 16, 2019, 02:10:15 AM »
An obligatory question: why not the latest release (or, even better, the latest nightly)?

Well, guess what - I installed 2.7.5 and it's played back at the normal speed now, heh. Thanks a lot.

Why I didn't try the newest earlier? I actually did - when I first discovered this issue I was at 2.7.1 or earlier mb. So 2.7.3 was the newest version I could get. And when it didn't help, I gave up, I suppose. Such "heavy" videos were a small part of my footage, so I just edited them through all this pain, and moved on. But lately I've got a lot of heavy footage on my hands, and it keeps piling on - so I thought may be it's time to ask around a bit. I didn't think about updating it again..
« Last Edit: September 16, 2019, 02:12:48 AM by MoriMoriMori »

eumagga0x2a

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Re: Version 2.7.3 (64bit) on Win7: very slow playback of 60fps x264 HD videos
« Reply #3 on: September 16, 2019, 06:59:48 AM »
I'm glad 2.7.5 worked for you. Leaving the update checker in Avidemux enabled might have helped here.