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Fwd: [Linphone-developers] Distorted Image using VPU encoder

From: Wu Xing
Subject: Fwd: [Linphone-developers] Distorted Image using VPU encoder
Date: Sat, 8 Aug 2009 09:48:01 +0800

---------- Forwarded message ----------
From: Wu Xing <address@hidden>
Date: Sat, Aug 8, 2009 at 9:19 AM
Subject: Re: [Linphone-developers] Distorted Image using VPU encoder
To: Code Warrior <address@hidden>
Cc: address@hidden

I am glad you got it. Shame for my poor codes with no comments.

I didn't give you videostream.c because I forgot it was correlative.

I did it a few months ago, to build a softphone demo. Now we are working on it again, because we need to display the video with Qt GUI.

On Fri, Aug 7, 2009 at 7:58 PM, Code Warrior <address@hidden> wrote:
Ohh..i got it. You are directly displaying the decoded frame buffer without hitting the display filter. Can you share videostream.c file as well ?

On Fri, Aug 7, 2009 at 4:53 PM, Code Warrior <address@hidden> wrote:

I've been thinking to integrate the VPU directly under medistreamer bypassing the ffmpeg. Your code really helped.
Many thanks for helping me out.

I'm still not able to display the received video at iMX27 even though the output from the board (video in the other direction) is correctly decoded and displayed by the Linphone running on my laptop (Windows version). [BTW, i did few changes in your videodec.c to enable videoout]. Did you try two way video calling ? What version of linphone, ffmpeg and vpu are you using ??

FYI. I'm getting a lot of error traces in the decode routine of Linphone (imX27). It says "Prescale Enable. not enough bs data".
But if i see the captured RTP packets, there is sufficient data in the frames. Marker bit is set as well (though it is not as consistent
across the frames as is sent by iMX27).


On Fri, Aug 7, 2009 at 7:08 AM, Wu Xing <address@hidden> wrote:

Glad to find some other one using i.MX27 here!

I've integrated the i.MX27's VPU code with Mediastreamer-2.1.0, using H.263 encoding, too.

I modified the videoenc.c and videodec.c, but i didn't meet the problem you said, it seemed to work fine with X-Lite.

I didn't know much about how YUV encoder works, so I just simply imitated the mxc_vpu_test code.

videoenc.c and videodec.c are attached here, hope they helps.

On Thu, Aug 6, 2009 at 11:01 PM, Code Warrior <address@hidden> wrote:

I'm running Linphone 3.1.2 over i.MX27 platform using VPU encoder (H.263 encoding). I've
integrated the VPU code with Linphone and have been able to get two way video. Problem is
the encoded video is distorted. Investigating more into the issue, i could find that all the I-frames
are displayed correctly but the following P-frames keep getting shifted towards the left. This corrupts the
whole running video. I forced the VPU to send all the I-frames and it worked. Clearly, there seems to be
some issue with encoding of P-frames. YUV image (captured image fed to the encoder) is perfect
and is displayed correctly. So no issue in the captured image as well.

Looks to me some issue with the VPU encoder parameters. While i'm investigating it, any help in this regards
would be appreciated. Has anyone encountered this issue earlier ?


Note: I know this is not an iMX forum. But i thought i could get some help here since it is related to Linphone.

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