2016-07-14, 15:35
Hello, (first time poster, please be gentle)
I've looked at lots of info on the web and the forum here regarding 'black screen & no video but audio' issues. I've been suffering from such a problem myself, and after a lot of experimenting I've found some patterns which trigger and solve/work-around the issue for me. Since this 'black screen' issue appears to be very long living I was wondering if my findings could be useful to anyone in debugging/solving (some of) these issues. Where should I post to see if anyone is interested to look into this (with me) to evaluate if my findings are of any use. I could run tests and provide log files etc. if a developer thinks this could be fruitful to investigate a possible bug.
brief summary:
Hardware/software setup:
KODI 16.1 git:c1c4b9e
running from openelec 6 (6.95.3 7.0) (generic x86_64)
on an (oldish) desktop pc with cpu core2DUO E6420, 2 GB ram
gfx: AMD RV710 (HD4xxx UVD2.2)
The issue:
When "allow hardware acceleration - VDPAU" is enabled, -sometimes- (not always!!!) when switching from one video source to another the video goes black, but kodi GUI graphics and audio play normally. This happens both with playing video files (mainly MKV from my NFS NAS) as well as TV streams by my tvheadend client.
(Retrying immediately or after a reboot usually solves the problem with videos, which IMHO proves it is not an issue with VDPAU not being properly supported by my hardware).
The easy way out of these problems is by disabling VDPAU acceleration as many tips/guides on the Internet also suggest, but to me this does not seem to be the right thing to do, if acceleration is supported it would be nice to be able to use it reliably.
I found the following patterns which IMHO suggest this could be some sort of video initialisation (race condition?) bug:
(setting for below description is VDPAU acc on, all sub options off (VAAPI off as well))
The problem consistently shows itself when I switch from an SD TV channel in tvheadend to an HD TV channel. The HD channel will show the black video (but GUI is visible and audio is there). Switching to the next HD channel makes the video (of that channel) visible, switchng back to the initial (black) HD channel will have proper video appear.
Another observation: When I also enable the VDPAU mpeg2 acceleration sub option, which affects the SD TV channel (ff-mpeg2video becomes ff-mpeg2video-vdpau), switching to the next HD TV channel will be black, but so will the next HD TV channel be and so on, and so on.
As a layman, it looks that the difference of the starting point of the SD channel (w/ and wh/ VDPAU) seems to have an impact on what happens with the next HD video display.
(With VDPAU completely off all channel switches give video, GUI and audio)
I realise that my reproduction scenario, involving the tvheadend client and therefore my personal tvheadend server setup, is not very convenient. I'm hoping the tvheadend part is not actually part of the problem (as similar issues occur with playing .mkv video files) but can be seen as a useful means to reproduce the issue and way to get video back after it occured. With video files I have no bullet proof reproduction scenario.
Let me know if I should drop this or if there is anyone or any place for this stuff.
I've looked at lots of info on the web and the forum here regarding 'black screen & no video but audio' issues. I've been suffering from such a problem myself, and after a lot of experimenting I've found some patterns which trigger and solve/work-around the issue for me. Since this 'black screen' issue appears to be very long living I was wondering if my findings could be useful to anyone in debugging/solving (some of) these issues. Where should I post to see if anyone is interested to look into this (with me) to evaluate if my findings are of any use. I could run tests and provide log files etc. if a developer thinks this could be fruitful to investigate a possible bug.
brief summary:
Hardware/software setup:
KODI 16.1 git:c1c4b9e
running from openelec 6 (6.95.3 7.0) (generic x86_64)
on an (oldish) desktop pc with cpu core2DUO E6420, 2 GB ram
gfx: AMD RV710 (HD4xxx UVD2.2)
The issue:
When "allow hardware acceleration - VDPAU" is enabled, -sometimes- (not always!!!) when switching from one video source to another the video goes black, but kodi GUI graphics and audio play normally. This happens both with playing video files (mainly MKV from my NFS NAS) as well as TV streams by my tvheadend client.
(Retrying immediately or after a reboot usually solves the problem with videos, which IMHO proves it is not an issue with VDPAU not being properly supported by my hardware).
The easy way out of these problems is by disabling VDPAU acceleration as many tips/guides on the Internet also suggest, but to me this does not seem to be the right thing to do, if acceleration is supported it would be nice to be able to use it reliably.
I found the following patterns which IMHO suggest this could be some sort of video initialisation (race condition?) bug:
(setting for below description is VDPAU acc on, all sub options off (VAAPI off as well))
The problem consistently shows itself when I switch from an SD TV channel in tvheadend to an HD TV channel. The HD channel will show the black video (but GUI is visible and audio is there). Switching to the next HD channel makes the video (of that channel) visible, switchng back to the initial (black) HD channel will have proper video appear.
Another observation: When I also enable the VDPAU mpeg2 acceleration sub option, which affects the SD TV channel (ff-mpeg2video becomes ff-mpeg2video-vdpau), switching to the next HD TV channel will be black, but so will the next HD TV channel be and so on, and so on.
As a layman, it looks that the difference of the starting point of the SD channel (w/ and wh/ VDPAU) seems to have an impact on what happens with the next HD video display.
(With VDPAU completely off all channel switches give video, GUI and audio)
I realise that my reproduction scenario, involving the tvheadend client and therefore my personal tvheadend server setup, is not very convenient. I'm hoping the tvheadend part is not actually part of the problem (as similar issues occur with playing .mkv video files) but can be seen as a useful means to reproduce the issue and way to get video back after it occured. With video files I have no bullet proof reproduction scenario.
Let me know if I should drop this or if there is anyone or any place for this stuff.
