We need a benchmark for codec testing

duartix — Sat, 11 Feb 2012 10:56:16 +0000

Seriously, shooting static torture charts doesn't cut it, nor does it bring any useful information on how a patch is doing except for Full Intra. We need something that is pure (uncompressed), has texture, has rich tones, has complex non linear motion (like fire or water), that is repeatable and easily accessible to everyone to play on a Full HD screen.

I've been searching the Web for flash animations to no avail. Does anyone have an idea or can come up with something that fits this bill?

An OpenCL/GL or DirectX demo perhaps?

AVCHD maximum image quality settings and testing

cbrandin — Thu, 18 Aug 2011 12:29:27 +0000

There is a thread for extreme AVCHD settings, a thread for Stable AVCHD settings, and a thread for low GOP settings, but no thread for maximum image quality settings – so I’m starting one.

Maximum bitrate and low GOP are not virtues in isolation; rather they are tools for achieving results. Taking maximizing bitrate, for example: if that is the only goal you are unlikely to achieve optimum results from an image quality standpoint. If you set the bitrate so high that you can’t raise the AQ value individual frame image quality won’t be improved much. Raising AQ results in smoother and finer details, and that’s a good thing. Without raising AQ the image will remain harsh.

What about testing with low-contrast subjects? One of the benefits of the new patches has to do with smoother rendition of gradients. This arguably has more to do with the beauty of images than extreme edge detail.

I’m going to take a somewhat different approach to developing settings – at least some of the time. The steps that seem logical to me are as follows:

1. Increase bitrate to a relatively conservative level; 44M for the 24H bitrate, for example.
2. Raise AQ to 3, or maybe even 4.
3. Increase FB1, FB2, and frame limit so that individual I frames can be bigger if needed.
4. Raise the bitrate to the highest stable value that supports these settings.

You could do a similar sequence involving low GOP. Set the bitrate to a higher – but not extreme - level, set the GOP, set the quality related settings, and then start raising the bitrate to higher levels.

For testing:

1. Test for stability under a variety of scenarios. One test of extreme importance is to put the camera on a tripod and use manual or AFS focusing –this can cause a failure instantly that may never show up when the camera is hand held.
2. Test for detail, but also test for smoothness (subtle gradients, low contrast subjects, etc…).
3. Test for motion fidelity. Make sure subjects in the frame all move smoothly from frame to frame; especially in low-contrast portions of the frame.
4. Test with very high shutter speeds as well as normal ones – this really stresses the codec.

If there are motion problems, back off on the AQ and try again, etc...

Maybe you have some ideas about testing procedures that measure image quality rather than a single metric like bitrate or GOP.

[EDIT] Per Vitaliy's suggestion I'm posting my 44M and 66M settings here - I'll keep them updated.

The main issue with both settings is spanning. At 24H neither set span - hopefully there will be a solution soon. The other modes with the 44M settings, as far as I know, do span with a good SD card. The 44M settings operate at 44M AQ4 for 24H, and the 66M settings operate at 66M AQ2 for 24H. The main difference between the two is that motion is handled more robustly with 66M. The other modes have been stable for me - but I have to confess that I have not tested the PAL modes very much. You can change the AQ settings without having to make other adjustments. Note, however, that 66M AQ4 is harder on the codec than 66M AQ2 and may pose stability, in camera playback issues, etc....

Chris

Pro: Direct testing requests

Vitaliy_Kiselev — Wed, 20 Jul 2011 19:11:19 +0000

This topic is decicated to my direct requests to make specific testing.

As all Pro topics it is intended to testers who want to help and understand that they are doing.
If you do not understand, either ask or just read and wait.

Active points:
* Try to format SD card using exFAT file system
* Check how it works in GH2
* Combine two large MOV files making them >2Gb, and >4Gb. Check if they can be played back in camera.

Tagged with testing - Personal View Talks

We need a benchmark for codec testing

AVCHD maximum image quality settings and testing

Pro: Direct testing requests