DRA718: Estimating RAM usage for video pipeline

Dominik Bozek

Part Number: DRA718

Hello,

I have to estimate memory usage for a video pipeline on DRA7xx using HW support .

Our product will have the following pipeline. I'm using gstreamer convention, but of course IP camera and DSS planes are not gstreamer components.

IPCam(1920x1080) ! rtspsrc ! rtph264depay ! h264parse ! ducatih264dec ! tee ! DSS.plane1 '1920x1080'
|
-- ! DSS.plane2 '640x360'

My problem starts with output from H264 decoder (ducatih264dec). The output from H264 decoder (video/x-raw) has to be used on two planes of different resolution (two displays connected to DRA7xx). In the pipeline above I used "tee" only to describe the video pipeline.

I have the following questions:

1) For my understanding the DSS (more precisely DISPC) is capable of scaling to expected resolution. Am I right?

2) Does the DSS need an extra buffer for scaling or it does scaling 'in-the-fly'?

3) May I feed both displays with one buffer in RAM (want to avoid coping output from H264 decoder for second sink)?

Regards
Dominik

over 4 years ago

0 Gaviraju Doddabettahalli Bettegowda over 4 years ago

TI__Genius 14305 points

Hi,

Please use the plugin "vpe" for scaling & it's HW based scaling IP. DISPC is not capable of scaling to expected resolution, so use the VPE plugin in the pipe-line for scaling.

Thanks

Gaviraju

0 Dominik Bozek over 4 years ago in reply to Gaviraju Doddabettahalli Bettegowda

Prodigy 30 points

Hi,

mentioned resolution are only examples. I expect DISPC to scale:

1920x1080 => 1280x720
and
1920x1080 => 1920x712

Is it possible? What is the minimum resolution available for DISPC?

My first tests of VPE shows, that it add huge latency. Didn't make strict measurement, but delay added by VPE was notable. What is the expected latency for VPE.

BTW, if DISPC is not capable of scaling to thous two resolutions, then I would need to use VPE twice in my pipeline. Is it ok?

Regards
Dominik

+1 Brijesh Jadav over 4 years ago in reply to Dominik Bozek

TI__Guru**** 479825 points

Hi Dominik,

DSS can support both of these downscaling.

Even VPE can support them. VPE downscaling will take approximately 10 to 15ms for downscaling this image.

Regards,

Brijesh

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DRA718: Estimating RAM usage for video pipeline