I am having problems with the image in vdr-sxfe, and initially I thought it was an issue with the settings relayting to video, but now I feel more confident that the root cause is in the DVB stream - which means it might be slightly off topic for this list if that is the case.
What I see from time to time (every ~5 minutes) is that an old image (from a few seconds ago) is suddenly displayed and then 'fades' away. Just how much corruption I get varies with vide osettings, but I can never get rid of it. Then I figured I'd do a recoding and replay a sequence which on live TV caused the corruption. And the corruption is repeatable whenever I pass that point in the recording.
Now it seems more like an issue of how the video decorder handles errors in the stream, but I would still like som help. Either in figuring out what causes the errors or dimish the impact on the picture.
At https://tyldum.com/vdr/00001.ts you can find a sample stream, and I get the corruption at 0:33-ish.
Source is DVB-C, using mantis-based tuner. femon reports 92% STR, 96% SNR and sometimes I see 1 in the BER counter. VDR version 1.7.17, packaged for yaVDR. Is it simply a bad stream, is there any ideas on how to remedy?
In case anyone else ever suffers from the same problem: It appears to be caused by an IO bottleneck. In my case I had video.00 and root on a software RAID1 with btrfs on top. Moving video.00 over to a separate disk (RAID0 with ext3 in my case) solved all my issues with the "old" image/frame re-appearing making the playback cluttered.
I tried going quadcore (even dedicating cores to each DVB card and VDR...), but the only thing that helped was moving video.00 off this array. It might be the software raid causing it or btrfs, or a combo.
Den 07.09.2011 21:49, skrev Vidar Tyldum:
I am having problems with the image in vdr-sxfe, and initially I thought it was an issue with the settings relayting to video, but now I feel more confident that the root cause is in the DVB stream - which means it might be slightly off topic for this list if that is the case.
What I see from time to time (every ~5 minutes) is that an old image (from a few seconds ago) is suddenly displayed and then 'fades' away. Just how much corruption I get varies with vide osettings, but I can never get rid of it. Then I figured I'd do a recoding and replay a sequence which on live TV caused the corruption. And the corruption is repeatable whenever I pass that point in the recording.
Now it seems more like an issue of how the video decorder handles errors in the stream, but I would still like som help. Either in figuring out what causes the errors or dimish the impact on the picture.
At https://tyldum.com/vdr/00001.ts you can find a sample stream, and I get the corruption at 0:33-ish.
Source is DVB-C, using mantis-based tuner. femon reports 92% STR, 96% SNR and sometimes I see 1 in the BER counter. VDR version 1.7.17, packaged for yaVDR. Is it simply a bad stream, is there any ideas on how to remedy?
ARGH! Root cause: 4k sector size while harddrives report 512byte sectors. Misaligned partitions will cause severe performance penalties [0] and block IO in the process - causing VDR to lose frames.
Thank you very much, WD, wasted a lot of time and money on this sillyness. Re-aligning the partitions for the 4k boundaries fixes all performance issues. Just a heads up to others who might have missed this detail.
[0] http://en.wikipedia.org/wiki/Advanced_Format#Advanced_Format_512e :
The translation process is more complicated when writing data that is either not a multiple of 4K or not aligned to a 4K boundary. In these instances, the hard drive must read the entire 4,096-byte sector containing the targeted data into internal memory, integrate the new data into the previously existing data and then rewrite the entire 4,096-byte sector onto the disk media. This operation, known as read-modify-write (RMW), can require additional revolution of the magnetic disks, resulting in a perceptible performance impact to the system user.
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Vidar Tyldum