MeGUI profile / list of x264 settings for slow target PC ?

[Poutnik]

Hi,

what MeGUI x264 profile, or settings to use,
if I want to target X264 encoding for slower PCs of my friends ?

So encoding speed does not matter (much),
but decoding speed can be critical.

Also, what is supposed minimal HW configuraion
to play H264 encoded PAL TV 720*576 (without DXVA) ?

[audyovydeo]

Hi,

what MeGUI x264 profile, or settings to use,
if I want to target X264 encoding for slower PCs of my friends ?

So encoding speed does not matter (much),
but decoding speed can be critical.

Also, what is supposed minimal HW configuraion
to play H264 encoded PAL TV 720*576 (without DXVA) ?

Dobre rano poutnik,

"slower PCs" is pretty vague. However, try targeting Baseline profile (like Apple Trailers) and you should be OK.

cheers
audyovydeo

[nm]

Hi,

what MeGUI x264 profile, or settings to use,
if I want to target X264 encoding for slower PCs of my friends ?
Resolution, bitrate, CABAC and inloop deblocking are the most significant factors. You could turn deblocking off while encoding and use CAVLC instead of CABAC, but compression will suffer quite a lot.

Also, what is supposed minimal HW configuraion
to play H264 encoded PAL TV 720*576 (without DXVA) ?
At 25 fps and less than 2 Mbps, 800 MHz Pentium III should be fast enough when using CoreAVC or libavcodec.

[Poutnik]

Note that I keep PAL resolution 720x576, using usually 1pass CRF Q26,
resulting typically 600-750kb/s ( 400-500 MB for movie )

[audyovydeo]

CRF Q26


Ouch ! when I used this value for PAL/SD resolution, I'd get a beginning of cartoon-like effect, with colours flattened out and grain disappearing. But if the quality is ok for you, then it's OK.


cheers
a/v

[Poutnik]

Ouch ! when I used this value for PAL/SD resolution, I'd get a beginning of cartoon-like effect, with colours flattened out and grain disappearing. But if the quality is ok for you, then it's OK.
cheers
a/v

Ahoj, Audyovydeo,

well, I almost exclusively process Air TV PAL captures,
some little noisy, some with interference,
so I denoise them a lot
by Degrainmedian or FFT3dfilter.

As consequence, influence of CRT-Q26 on quality is less, compared to DVDrip.
But, anyway, I decided even before to start using Q23-24 for it.

[Blue_MiSfit]

Turn off CABAC if you are even thinking of doing HD on a slower PC. I'd never sacrifice deblocking..

Also, do try to keep the bitrate low, and use VBV to limit bitrate spikes (with a 2 pass encode obviously).

Finally, the decoding and rendering chain is a HUGE thing when it comes to older PCs. If the older PC has a GPU that supports pixel shaders, I usually find Haali Renderer to be very fast. Otherwise, overlay mixer seems like the only good option.


Also, what is supposed minimal HW configuraion
to play H264 encoded PAL TV 720*576 (without DXVA) ?


For decoding, CoreAVC made ~1.5mbps 480p quite playable on my clunky old 800MHz P3 laptop. That even included CABAC etc! The new DivX H.264 decoder is quite fast, but I'm not sure how it would perform on slower, single core CPUs.

I'd say a 1 GHz P3 should be your minimum baseline for acceptable performance for SD PAL at reasonable bitrates.

~MiSfit

[qyot27]

Those kinds of concerns are why I tend to rely on insane profiles - mainly because they can keep the bitrate down very easily, even if they take forever to encode. It's not a panacea for decoding ability, though. But if you can manage to keep the bitrate contained, even using the advanced features of H.264 can work well on old setups. Basically I noticed that Advanced Features + High Bitrate = Decoding Nightmare, but Advanced Features + Low Bitrate (possibly due to said features) = Generally OK. The type of content makes a huge difference here - if there's a lot of noise or heavy motion, then the bitrate will spike and cause problems, while mostly static scenes will be relatively okay on playback. For some of the stuff I have that's encoded at 23.976fps or 29.97fps using insane settings, my computer (which has a Celeron 2/Pentium 3 Coppermine, 1GHz, 256 MB RAM, 100 MHz FSB) can decode at roughly 19fps or so using libavcodec. So for some videos a lag is more noticeable than in others. This is just at 480p, though, and I generally encode with CRF 18.

Of course, it is also true that not using some features, notoriously CABAC, will raise the maximum bitrate that the video can be encoded with and still be playable on an older setup. It ultimately comes down to how efficient you want compression to be.