DEI LINK affects video quality?

bollgo

Intellectual 390 points

hi,all.

My env: dm8168 and dvr rdk 4.0

My chains: vcap->dei->sw->vdis.

My capture : use computer desktop signal.

we can be found the image quality not as good as the original (my capture desktop).

when I delete the DEI link. my chains:vcap->sw->vdis ,that the video quality is good as the original.

the capture desktop image(add DEI link):

the capture desktop image(delete DEI link):

my question:

(1) To add the DEI link may affect the image quality ?

(2) if I must use DEI link (because I want to dynamically change the encode resolution), So, how can I fix the problem make the image quality better.

　Looking forward to your help.thanks.

over 11 years ago

0 Steve Clynes over 11 years ago

TI__Mastermind 43875 points

I am not sure that the DEI link supports 444 format, so you will possibly see decimation smearing due to 422 decimation.

I am not 100% sure on this but it might be something you can check.

BR,

Steve

0 Brijesh Jadav over 11 years ago in reply to Steve Clynes

TI__Guru**** 482245 points

Hi,

DEI driver does not support 444 output, so it has to be either yuv422 or yuv420 output format.

Could you tell what modules are enabled in DEI Link? Are you using it to do deinterlacing? or is it just scaling and format conversion?

Rgds,

Brijesh

0 Sivagamy Govindasamy over 11 years ago in reply to Brijesh Jadav

TI__Expert 6950 points

Hi,

I believe the issue under discussion is similar to the issue you have mentioned in this post - http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/t/325655.aspx.

I used your input yuv (http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/717/3630.before_5F00_dei.7z) with standalone hdvpss dei scale example & dvr rdk.

1. Tests in Standalone HDVPSS example

There is no quality degradation if 1:1 coefficients are selected & scaler is enabled (scCfg.byPass = FALSE).

I am attaching the output generated with m2mDeiScale_test.

5040.BYPASS_FALSE_1_1_COEFFS_deiDeiSc2Wb1Ch1WbOut_yuyv422_prog_packed_1920_1080.rar

You can verify this with standalone example. Attaching the changes to enable 1080P input (as per your requirement).

5050.Sample_Code.zip

2. Test with DVR RDK

- In DVR RDK also, include the patch to select correct coefficients (shared by Badri).

- Comment out DeiLink_drvSetScCoeffcs() routine which is redundant now. DeiLink_drvSelectCoeffs() present in patch should do the job.

There is no quality issue observed for the same test parameters.

0 Sivagamy Govindasamy over 11 years ago in reply to Sivagamy Govindasamy

TI__Expert 6950 points

Hi,

Attaching output with degraded quality for the test case where wrong coefficients are selected (in default m2mDeiScale application) to see the difference due to coefficient selection.

8105.BYPASS_FALSE_8_16_COEFFS_deiDeiSc2Wb1Ch1WbOut_yuyv422_prog_packed_1920_1080.rar

You can compare the output with http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/717/5040.BYPASS_5F00_FALSE_5F00_1_5F00_1_5F00_COEFFS_5F00_deiDeiSc2Wb1Ch1WbOut_5F00_yuyv422_5F00_prog_5F00_packed_5F00_1920_5F00_1080.rar

0 bollgo over 11 years ago in reply to Sivagamy Govindasamy

Intellectual 390 points

Thank you very much for such a detailed answer.

my env: Test with DVR RDK(links:vcap-dei-sw-vdis)

(1) According to your answer, Comment out DeiLink_drvSetScCoeffcs() routine which is redundant.

Image quality is better, but still don't feel the effect of the original(Desktop signa) .

(2) include the patch to select correct coefficients (shared by Badri).

I’m so sorry that I don’t find it. Can you say that again.

(3) To add DEI link will affect image quality ? The problem has cost me a lot of time.

(4) use DEI link for Dynamic change encode resolution,Are there any other way?

0 Badri Narayanan over 11 years ago in reply to bollgo

TI__Guru 59700 points

First apply the patch: http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/717/7444.dvr_5F00_rdk_5F00_deiscalercoefficients.patch.txt

Then comment out call to DeiLink_drvSetScCoeffcs which is no longer required.

bollgo said:
(3) To add DEI link will affect image quality ? The problem has cost me a lot of time.

DEI link will not affect quality as clearly shown by the images shared by Sivagamy.Enabling peakingFilter actually enhances brightness and improves quality as seen in the images shared.

bollgo said:

(4) use DEI link for Dynamic change encode resolution,Are there any other way?

You can use SclrLink or DEI link or use VIP inline scaling to change resolution. None of these affect video quality.

0 bollgo over 11 years ago in reply to Badri Narayanan

Intellectual 390 points

Badri, thank you for your answer.

I have modified the code(as you suggest).

Effect is much better, but did not reach the effect of the original(links:vcap_vdis)

vcap-vdis:

vcap-dei-vdis:

It is easy to find, if I add DEI link , Image is produced with some fuzzy.

I modified links To test: vcap- sclr-vdis. However ,Image quality like above(links: vcap-dei-vdis), and did not achieve the original effect.

Hope to provide better advice, thanks.

0 Brijesh Jadav over 11 years ago in reply to bollgo

TI__Guru**** 482245 points

Hi,

Scalar does multi tap polyphase filtering, so output will change, it will not remain exactly same as input. If you want exactly same output for 1x scaling factor, use 1x scaling coefficients.

Rgds,

Brijesh

0 Sivagamy Govindasamy over 11 years ago in reply to Brijesh Jadav

TI__Expert 6950 points

Hi,

The difference in quality when using 1:1 scalar is because peaking filter & edge detect are enabled in example code.

Set scCfg.enablePeaking = scCfg.enableEdgeDetect = FALSE.

Output is exactly bitmatching with input in this case.

0 bollgo over 11 years ago in reply to Sivagamy Govindasamy

Intellectual 390 points

Badri , Sivagamy, thank you.

Following your suggestion, I have resolved this issue.

(1) other question: I will use the NSF link, Implement YUV422 into YUV420, (mylink: cap - NSF - dis). I found the image quality is affected. Is there any way to solution to this?

Thanks again!

0 Badri Narayanan over 11 years ago in reply to bollgo

TI__Guru 59700 points

Check nsfCreateParams.bypassNsf is TRUE. If TRUE then nsf is only doing 422I to 420 conversion and any quality reduction you are seeing is to downsampling. Nothing can be done about this.

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DEI LINK affects video quality?