iMX6 VPU MJPEG Thumbnail generation

[kristofferglemb]

Hi there,

When reading the VPU API Reference Manual one gets the impression that the VPU can generate thumbnails during JPEG encoding since the EncMjpgParam struct has thumbNailEnable and thumbNailWidth/Height fields.

However the manual is very light on the details of this thumbnail and I'm unable to get anything to work. My input buffer is in YUV422 horizontal format, and I specify a thumbnail size of 128x96. First I thought the thumbnail would appear in an APP0 marker in the generated header, but no APP0 is generated. Instead I gave addresses to two buffers for subsampled images to vpu_EncRegisterFrameBuffer() but nothing is written to these buffers.

Can someone enlighten me to how this is supposed to work?

Best regards,

Kristoffer

[joanxie]

As I known, Current our implement is seek to the 5th second to get thumbnail.

If the file canot support seek , you may get no thumbnail.

[kristofferglemb]

Hi,

Sorry I don't understand. No file is involved. I use the imx-vpu low level API.

When doing vpu_EncOpen() I specify:

openParam.EncStdParam.mjpgParam.mjpg_thumbNailEnable = 1; 

openParam.EncStdParam.mjpgParam.mjpg_thumbNailWidth = 128; 

openParam.EncStdParam.mjpgParam.mjpg_thumbNailHeight = 96;

And I give the VPU buffers for subsampled images in vpu_EncRegisterFrameBuffer().

But I don't get any thumbnail written in that buffer, nor in the bitstream buffer.

/Kristoffer