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Haswell Quicksync lookahead?

Michael_Schmidt
Beginner
576 Views

http://newsroom.intel.com/servlet/JiveServlet/previewBody/3880-102-1-6896/WP-HD-Graphics-4200.pdf

I'm curious about the lookahead feature from Haswell. Is that a driver feature or it requires encoder integration for existing software? What encoder did Intel use in their comparison? It's not clear to me if I can use let's say MediaEspresso and lookahead is enabled or not.

0 Kudos
27 Replies
Petter_L_Intel
Employee
85 Views

Hi again Michael,

Regarding the quality discrepancy between QCP and LA you reported. Our encoder experts have explored this further and acknowledge that LA result in lower quality vs. CQP for this content, partially due to LA's obligation to maintain a local bitrate. 

We do not have any immediate plans to address this specific scenario by changes to LA. But we will explore possible ways of improving future revisions of LA to handle this content and others better.

Regards,
Petter 

Cao_j_
Beginner
85 Views

Recently I use sample_encode. exe has carried on the test of LookAhead, I downloaded the latest Intel SDK, and tested on the latest machinery, CPU: i7-4770, Os: Windows 7, Graphics Devices: HD 4600 Graphics, but I found that using the LookAhead get worse picture quality than without using LookAhead,the following is my command line arguments:

Use LookAhead:sample_encode.exe h264 -i C:\yuv.yuv -o C:\test_la.264 -w 720 -h 576 -hw -d3d -f 25 -b 1000 -u quality -la -lad 30 

not use LookAhead:sample_encode.exe h264 -i C:\yuv.yuv -o C:\test.264 -w 720 -h 576 -hw -d3d -f 25 -b 1000 -u quality 

the yuv.yuv is 720*576

Petter_L_Intel
Employee
85 Views

Hi Cao,

Can you please share with us the graphics driver version you are using.

Also, if possible, please share your raw input YUV file since the quality looks the be dependent on content in your case,

Regards,
Petter 

Cao_j_
Beginner
85 Views

Hi Petter,

First of all, thank you for your reply,my graphics driver is 15.31.17.64.3257, and the color of the YUV file is YUV420, width is 720 * 576, the original rate is 8000,I intercepted three images as the result of the experiment.And second ,i want to know that how to get better quality In the hardware encoding mode. 

Petter_L_Intel
Employee
85 Views

Hi Cao,

There is a more recent driver available from some sources that have known issues with LA, but the driver you are using is good for LA usages. 

Your input content seems to be from a deinterlaced source with lots of jagged artifacts. It may be that the LA algorithm has some trouble with such content. Again, if you can please share the exact raw data (or part it) it would help us reproduce on our side.

Regards,
Petter 

Cao_j_
Beginner
85 Views

Hi Petter,

This is the part of YUV file.

Cao_j_
Beginner
85 Views

Hi Petter,

The Yuv file you  can download frow here  http://yunpan.cn/QbiCJC9PyVraf

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