Go Pro 3 footage – Rendered in AVC MP4

[Dave Osbun]

Two-pass rendering is always worth it, if you can live with the extended render time. If you’re looking for the best video quality, then you’ll want to enable this.

GPU acceleration doesn’t affect video quality, just render times (if GPU is supported). Hence its name.

By choosing variable bit rate, you might have a slightly lower render time, but if you’re going to enable two-pass rendering, you might as well choose constant bit rate and crank it to 11!

I’m sure some of the super-experts on here, like John R., can give more detailed (and probably better) advice on this subject since i’m not an expert.

Dave

[Darren Hugh]

Thanks for the tips!

Ive been testing them out as well. Only struggle I am facing now though is video lagging when playing with media player classic.

Ive got a pretty bad ass computer and never experienced lagging like this.. So im not sure if its the settings or if its just how it is for some reason.

[Norman Black]

The Mainconcept AVC encoder is actually three separate encoders.
CPU, OpenCL and CUDA.

Each is independent code and there will be quality differences. The differences should have nothing to do with frame rate. Only the quality level within the frames.

The highest quality is the CPU only encoder. The OpenCL and CUDA encoders are similar and not as good. If you really want to know the ugly details. Note that any visual differences will only show at lower bitrates.

Codec comparison

It’s kinda a waste to use two pass and have average and max bitrate the same. Just use one pass in this case. With two pass and average much lower than max bitrate, like the default templates, you allow the encoder to use lower bitrates when it can so it can save bitrate for those portions it needs a higher bitrate to preserve visual quality.

[Dave Osbun]

It’s been a while since i’ve come across clips where the video & audio were not in sync, but it always came down to the computer they were being played on (not enough system power). Somethings not right if you have a modern, powerful system.

Is this happening when playing the video full screen? If you decrease the size of the player window, to maybe 25% of original, is it still out of sync?

Dave

[Darren Hugh]

Thank you for your help.

Ive been testing some more.. You know the profile option. I was reading something about all players reading “high” normaly now, so it shouldn’t be a problem.

I tried using “main” now, and it looks like the flow is better tbf.

Am I right in suggesting these settings will render out the video as good as it gets? Or are there ways to get it even better?

[Norman Black]

Better/best are subjective, but the best AVC/H.264 encoder out there is the x264 encoder. However at the higher bitrates you are using I doubt you would see much difference. The better encoders are obviously better at lower bitrates but most are very similar at higher bitrates.

One tweak you could try that I did not previously mention is to change the number of slices to 1 from 4. 4 slices is only needed if you are going to burn a Blu-ray at level 4.1.

The jumpy nature of your playback may have been due to the player not able to decode at full speed and so it stuttered briefly. You are at very high bitrate and 60p which takes a lot of power to decode.

What were you playing back on? PC, player, player settings like DXVA decode.

[Darren Hugh]

Right so I did some tests again.. In Media Player classic the video clip lags about. Audio is out of synch, but when playing with windows media player its alright!

Ive noticed though that with alot of movement and FX the “flow” doesnt seem to look as good as when I use Xvid (don’t ask). What might be the cause of that is that as you say it takes alot out of the computer..

Is there any way of fixing the lag though? If I’m giving the video to friends of mine, it wont do them any good if it keeps lagging for them as well..

EDIT:

Playing with vlc with the computer monitor looks fine. When watching on TV trough a HDMI it lags..

Media Player classic lags every now and then on both.

Media Player looks good on computer monitor, but wont even show up on TV. Ha.

[Norman Black]

Xvid is a simpler codec which is easier to decode and is therefore less likely to have a playback problem at high bitrate and frame rate. Xvid will not have the same quality at the same bitrate as AVC. It will be close.

I use Media Player Classic Home cinema on my machine, 2.9Ghz core i7, and it plays my GoPro 1080p60 30Mbps files fine as far as I can tell. A little less bitrate than your file. This is with a pure software decode. There are options to enable DXVA hardware decode but it is not necessary on this machine with anything I do. I don’t bother with any other players.

On my nettop (Atom CPU) everything AVC must use hardware decode (DXVA) for smooth playback. This is playback to my TV via HDMI.

HDMI should not be a bottleneck in any way. Computer monitors can be hooked up via HDMI. The bottleneck is really how fast is the CPU to decode on playback given the high bitrate and framerate combination you have chosen.

My only suggestion, beyond a power CPU, is to enable DXVA hardware decode in the software decode seems like it has an issue playing smoothly. How you do this depends on the player. Some might do it automatically and some manually. In my MPC install it is controlled in the LAV video decoder options.

The only other possible suggestion is to back off the 59.94 down to 29.97. This cuts some frame overhead and you can cut the bitrate. Both helping playback.

[Darren Hugh]

Cheers for detailed feedback. I’ll do some more testing and decide what I do..

Ive got one final question though..
Up until now Ive been rendering my movie in small parts, as Xvid took aaaages to render, and I hadn’t really got hold of the mp4 codec before now. When I rendered small parts with Xvid there would be no further compression when I was rendering all the small parts into one. When I try using same settings with the mp4 files it starts rendering as normal, with the same rendering speed.

Do you know if this will affect the outcome quality? I know people say you shouldnt re-render, but with xvid there was no compression at all, but there seems to be with mp4. I tried searching online for answers, but couldnt find any accurate help.

Thanks

[Norman Black]

Yes, when you render from a lossy format to a lossy format you do get loss. This is technically true, but you may not be able to see it. Maybe only if you freeze frame and pixel peep. A far cry from viewing at 30p or 60p frame rates. You are also using very high bitrates which minimizes damage. Rendering through multiple generations is more likely to have damage but you are only doing one extra render.

So lossy -> lossy does damage, but if you cannot see it then should you really care? You can do a quick test for yourself.

Take a clip A. Render it out at your settings from your source(s). Now bring clip A in and render clip A again at the same settings. Now compare the first generation to the second.