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Help to track down DVR/Live TV frame skip issue

Added by F OM about 8 years ago

Finally had what I thought was perfect setup for me but when recording a programme, I have noticed the following:

DVR'ing a programme on a DVB-T channel and then while simultaneously watching a programme on the DVB-S2, the picture will stall for a frame or 2 every 15 seconds.
The DVR recorded programme skips no frames on playback.
When the DVR is finished, there will be no further frame skipping as described above.

Looking for advice on how I can track down whats causing this issue as the tvheadend setup is otherwise flawless (for me)
i.e. What are the logging option or performance I should keep an eye on?

Setup:
Nvidia Shield TV running SPMC and TVHeadend backend (HTS Tvheadend 4.1-2140~gf34fac1)
2 x RTL2832 DVB-T usb tuners plugged into shield.

Sat-IP Digibit R1 DVB-S2 tuner (with Satip-axe firmware)

DVR records to a local class 10 128GB SD card in the Nvidia Shield.


Replies (5)

RE: Help to track down DVR/Live TV frame skip issue - Added by Robert Cameron about 8 years ago

As a guess, it sounds like the problems are related to saving 2 streams to the SD card are the same time, or some other issue with bandwidth. Does the USB and SD card slot share the same bus? Do you have the same problem when using both DVB-T tuners at the same time, or is it only when using one DVB-T and one DVB-S2? Are you using timeshifting buffers?

RE: Help to track down DVR/Live TV frame skip issue - Added by F OM about 8 years ago

Thanks for the reply.

Not recording 2 streams, recording one and watching another.

1. Recording DVB-T stream via USB tuner
2. Watching Sat>ip DVB-S2 stream which comes over the LAN network

Only happens using the DVB-T(USB) and DVB-S2

Good idea, will check re USB buses.

Don't have timeshifting in this version of TVH but would enabling buffers help or hinder? Where can I enable them?

Update:
USB and LAN interface are on separate bus.
Can't determine re SD card yet (android so lsusb commands are limited)

RE: Help to track down DVR/Live TV frame skip issue - Added by Robert Cameron about 8 years ago

Could also be a problen with the SD card and/or format. What FS is the card formatted as? F2FS? ExFAT?

RE: Help to track down DVR/Live TV frame skip issue - Added by F OM about 8 years ago

Pretty sure its FUSE. (androids adoptable storage)

RE: Help to track down DVR/Live TV frame skip issue - Added by Robert Cameron about 8 years ago

FUSE is not a filesystem, it is Filesystem in USErspace, meaning the filesystem drivers run in userspace as opposed to in the kernel.

The filesystem is how the files are stored and laid out on the physical storage device. F2FS is a filesystem specifically created for flash memory (F2FS = Flash Friendly Filesystem) by Samsung. ExFAT is Microsoft's FS that was originally created with flash in mind (way back in the early WinCE days). While Ext4 (which is often what it used on-device for Android filesystems) is good, it is not really the best for flash media.

But, if you are using it with Android's Adaptable Storage feature, I am unsure what filesystem underneath it all is. (A quick internet search yielded no details.) However, if it does turn out to be the SD card (which is not a good choice for a DVR to store things because of the limited amount of writes they can sustain), there is another option.

You can format the SD card as a better FS, such as F2FS, and when you insert it into the Shield, just choose Portable storage instead of Adaptable storage.

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