Mythfrontend Playback FFmpeg hangs

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gabs
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Joined: Sat Sep 06, 2014 6:55 am
Germany

Mythfrontend Playback FFmpeg hangs

Post by gabs » Sat Sep 06, 2014 7:17 am

Hello to all,

I am using MythTV for years on a laptop but I have switched now to a mini computer (odroid-u3).
Using the git version, main branch, from yesterday (35dca9eb3fd043044efc70b8c30a80e64a9af62e) mythtv compiles fine on the ubuntu 14.04 that is running. I also used some older states during the last week.

The hardware of the odroid is strong enough to play my videos (h264 mkv, divx mkv, etc.) and also DVB-S recordings that were created with mythtv using ffplay even with intermediate CPU usage (I can compile other stuff during playback without problems).
Anyway, the playback with the internal player of mythtv is not working fine: the video hangs / skips frames (although in live tv the framerate is shown to be 25 fps) while the audio works fine. This applys to liveTV and playback of my videos.
When I change the MythVideo player from internal to ffplay the problem disappears but it does not seem to be possible for live TV and I would like to use the internal player due to its better user interface.

So my questions are:
To me it looks like the internal player also uses ffplay (or mythffplay) which both work fine as standalone players - any idea why the internal player does not work ?

I played around with the options in mythfrontend (opengl, xshm, xv-blit, vaapi and so on): some work better some are worse but none is fine.
Which of these options is ffplay using?

Is there a way to use ffplay directly for live TV in mythfrontend as a kind of workaround?


thanks a lot for mythTV and for any help provided here!

regards,

Gabriel

splurben
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Joined: Sun Sep 07, 2014 4:15 am
Australia

Re: Mythfrontend Playback FFmpeg hangs

Post by splurben » Sun Sep 07, 2014 5:37 am

What is the video adapter in odroid-u3? Can you open a terminal and post output of

Code: Select all

sudo lspci | grep VGA

gabs
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Joined: Sat Sep 06, 2014 6:55 am
Germany

Re: Mythfrontend Playback FFmpeg hangs

Post by gabs » Sun Sep 07, 2014 7:35 am

Hi,

the odroid U3 has a Mali 400 Quadcore as GPU and a Samsung Exynos 4412 Quadcore as CPU.
Of course this is not really strong and fast, but as I have written it is indeed fast enough for playing the videos with ffplay also when mythfrontend is running.

lspci is not available on this board.

regards,

Gabriel

gabs
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Joined: Sat Sep 06, 2014 6:55 am
Germany

Re: Mythfrontend Playback FFmpeg hangs

Post by gabs » Thu Sep 11, 2014 12:24 pm

The best performance is reached when I reduce the screen resolution to 720p and use xshm with linear blend.
Still this is much worse than ffplay on its own. Interestingly, HD works better than SD TV.

I'd still like to know whether I could use an external player for live TV and why the ffplay command is much better than the internal player although it seems like it uses this.

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rwagner
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United States of America

Re: Mythfrontend Playback FFmpeg hangs

Post by rwagner » Thu Sep 11, 2014 2:30 pm

gabs wrote:I'd still like to know whether I could use an external player for live TV
No.
gabs wrote:and why the ffplay command is much better than the internal player although it seems like it uses this.
Considering they're both using the same decoding library, the difference has to be in how the decoded video is being rendered to the screen.

gabs
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Joined: Sat Sep 06, 2014 6:55 am
Germany

Re: Mythfrontend Playback FFmpeg hangs

Post by gabs » Fri Sep 19, 2014 7:26 pm

Hi,

I recompiled mythTV and tried all the video playback options again (xv-blit, opengl, opengl-lite, xshm, ...). they all hang.
the key problem is that I get such messages:

Code: Select all

2014-09-18 20:33:37.538065 E  VideoOutputXv: Falling back to X shared memory
 video output.
(or falling back to X11 over a network socket). The frontend then even says that this might be slow, leading to xv dropping frames.
Unfortunately, there is no message that says why the video output is falling back to another option. Is it normal that I get errors from xv when openGL is selected as output method?

Any idea, how I can find the real problem, i.e. why it falls back to xshm?

ffplay uses SDL which works perfectly. There is no way to use SDL in the frontend, is there?

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