Problems with IMX6Q dual display and BT656 output

[timothybean]

Hi All,

Hopefully some smart Freescale people can help me out here. I recently upgraded my Nitrogen6x board to include a ADV7391 analog output. This is attached to the parallel RGB port.

When working with my L3.0.35_12.09.01_GA version kernel, HDMI output worked perfectly. I am using Gstreamer to decode live video streams. This worked at all resolutions (480p-60, 720p-60, 1080p-60) without issue.

To incorporate the BT656 patch:

Patch to support BT656 and BT1120 output for iMX6 BSP

I have to upgrade to the 1.1.0 release of the kernel. Since that point my HDMI video has not been running right. Frame rate of the display is off so I have to drop frames to keep up with the live stream. I have moved the hdmi over to IPU1 and even tried to change the clock that IPU 0 was on per Qiang Li's (write patch for BT656) advice. Still, no change.  If I change the disp-width to 1272 then the video shows up with good visual quality, but I have to drop frames to keep in sync with the display. I did not have these problems at all on the previous kernel version. Here is what I see on my HDMI display is I run video that is native format to the display (ie. 720p video -> 720p display):

This issue seems to happen in the 1.1.1 release even without the BT656 driver installed. Something is very different than my previous kernel version.

I need to get this resolved ASAP as my client is waiting on finished product.

Thanks

Tim

Message was edited by: Timothy Bean

[qiang_li-mpu_se]

There are some update for dual display support in https://community.freescale.com/docs/DOC-94019, since you said the issue can also be duplicated without the BT656 driver, can you tell us how to duplicate it with signal HDMI output mode?

We need identify it is a kernel driver issue or MMcodec issue first.

[timothybean]

I just play from an RTSP video source:

gst-launch rtspsrc location=<IP>/stream ! rtph264depay ! vpudec low-latency=true ! mfw_v4lsink sync=false

That will produce the attached picture. If I do:

gst-launch rtspsrc location=<IP>/stream ! rtph264depay ! vpudec low-latency=true ! mfw_v4lsink sync=false disp-width=1272 then the picture looks OK. Changing the disp-width does something to it.

Also, at 1080P (display at 1080P and video at 720P) I end up with memory and latency accumulating in the pipeline. Enough to be unusable. As if the display cannot keep up with the video frame rate (30 fps). On the L3.0.35_12.09.01_GA kernel I did not experience any of these problems.

This is with corresponding LTIB releases and matching gstreamer elements (previous kernel 3.0.2 and current kernel 3.0.5)

I should also mention these are LIVE video streams from an IP camera. NOT from files. Playing from a file may show good results, but I have not tried. The video is H.264 720P or D1 resolution and MP L3.1 encoding. Bit rate is from 256 kbps to 8 Mbps.

Thanks

Tim

[qiang_li-mpu_se · Accepted solution]

If the issue only happens on RTSP playback, I think it is not HDMI or BT656 output related.

For the simple way, you'd better manully porting the BT656 patch to L3.0.35_12.09.01_GA kernel.

[timothybean]

This problem has nothing to do with RTSP. But if I change the mfw_v4lsink disp-height to 8 pixels less than the output resolution then it displays good video. Why do I need to do this? Is there any alternative to doing this to get full video output?

Tim