DM365 Encode Demo YUV4:2:0 issue

Jesus Lopez

Hi all,

I am triying to modify the Encode Demo included in the DVSDK 2.10, using montavista Linux and the DM365 processor. To acces the frame data I modified the file Framecopy.c file in /home/jlopez/dvsdk_2_10_01_18/dmai_1_21_00_10/packages/ti/sdo/dmai.

The data I am using is in YUV420 semiplanar format which means that frame data in memory is ordered as follows: Y1,Y2,Y3,...Yn,CR1,CB2,CR2,CB2,..,CRn,CBn. To check I set to 0 all Cr,Cb data and I expected to get black&white video but what I've got instead is monochrome green video.

Any suggestions what could be wrong?

Thanks in advance

Jesus

over 15 years ago

0 Miguel A. Alanis over 15 years ago

TI__Genius 9490 points

Jesus,

please take a look at the following forum guidelines so you can file the right questions to the right forums. This is clearly another linux related question when running the demos/drivers etc.. https://e2e.ti.com/support/dsp/davinci_digital_media_processors/int-dm3x/f/102/t/34529.aspx

regards,

miguel

0 Niclas over 15 years ago in reply to Miguel A. Alanis

TI__Expert 3220 points

Hi Jesus,

The YUV422 "semiplanar" format on dm6467 does not necessarily mean that the CbCr plane comes directly after the Y plane. See the VDCE user's guide which came with the PSP release for a detailed explanation of the color format and how the driver expects your data to be formatted.

Regards, Niclas

0 Anshuman Saxena over 15 years ago in reply to Miguel A. Alanis

TI__Mastermind 19985 points

Jesus,

Chroma value for Cb and Cr ranges from -128 to 127. Value of 0 corresponds to green color and hence you saw green color on the image. You should put 0x80 or 0x7F to see the gray scale image.

Regards,

Anshuman

PS: Please mark this post as verified, if you think it has answered your question. Thanks.

0 Jesus Lopez over 15 years ago in reply to Anshuman Saxena

Prodigy 220 points

Yes, you were right, 127 is equivalent to chroma 0, becuase the values were in 2s complement. Now I get black and white images.

Thanks

Jesus

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DM365 Encode Demo YUV4:2:0 issue