WebIF|Opt+|Set Thumbnail| very slow on HiDef recordings

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SunnysideUK

Member
Hello readers. My first posting here.

Several years with the Humax HDR-Fox, I now have 3 (and currently, an unconnected HD-Fox) I have several problems that I'd like some help on please.
I'll post one at a time, here's the first!

I currently set a thumbnail after setting a bookmark at my desired image.
With StdDef recordings I get 5 boxes that populate within about 10 seconds, depending on the recorders current activity.
Selecting Use, will automatically do so and return to the browser listing pretty pronto.
However, with HiDef recordings I get 3 boxes that typically take 2-3 minutes to populate and similar time when I select Use.

Q. Is this normal?
If not what can I do to resolve this?

P.S. fixdisk recently ran. Typically takes 25-35min depending on amount of recording usage. All drives are standard 500GB.
 
I suspect this has something to do with decryption. The generation of sample frames to choose from requires on-the-spot selective decryption (unless the recordings are pre-decrypted), and this is obviously a more demanding process for HiDef (although I'm not sure it's tens of times more demanding). Frame extraction is also more demanding, so perhaps that makes up the rest of the difference.

Something you could try is to decrypt before going to thumbnails, and see how much difference that makes. At least that should indicate where the problem might be.
 
Black Hole: I only do this on decrypted files, its the last process I would do post normal.

The problem is consistent on HiDef recordings and on at least two on my recorders and probably the older one too (but currently its WebIf is not responding again and its in current use. I'm looking into this WebIf problem too re. ref. https://hummy.tv/forum/threads/webif-loading-stalls.10384/ and you suggesting files: /mod/etc/webif.db or /mod/etc/queue.db. More on this on a seperate thread if I have no success!)).

I just timed it on my main unit while it was half-awake (recording UFO) on BBC's The Planets 1.13GiB and it took 3 minutes 38 seconds, and then all 3 box images were populated in one go. These files are 'shrunk' which happened automatically when I cropped out excess recording at the start and end.
 
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Some further information, should it be useful;
This morning I recorded a 15 minute section of BBC Breakfast in HiDef (LCN:101).
After auto-decryption (no shrinking, etc) I tried the 'Set Thumbnail' option and it took 2 minutes 5 seconds for the boxes to fill (again, all in one go), the box wasn't doing anything else and I have it automatically go to LCN:100 at start (Freeview channel) to lessen its load.
 
I tried setting a thumbnail at 50 minutes (-t 3000) into a HD recording and a SD recording of the same programme.
The HD version took 1 minute (01:01) while the SD version only took 2 seconds, both files decrypted
 
MymsMan said:
I tried setting a thumbnail at 50 minutes (-t 3000) into a HD recording and a SD recording of the same programme.
The HD version took 1 minute (01:01) while the SD version only took 2 seconds, both files decrypted
Click to expand...
Hmm, thanks for that information.
So HiDef is much longer than StdDef takes, so probably normal, although yours is still much faster than mine.

My standard disk is decrypting at about 5.4 to 7.5 MiB/s.
(the HiDef BBC test decrypted at 5.42 MiB/s, StdDef UFO at 6.06 MiB/s but last weekend's F1 HiDef was at 7.5 MB/s. difference maybe due to transmitted bits/sec quality? anyway...).
Wondering if you have a faster disk? Maybe the 1TB disk is faster (although I'd have thought the SoC would be the bottle neck).
 
Do you have the Thumbnails package Installed?
With that package thumbnails can be automatically generated.
For my timings I am using the Queue for Thumbnail Generation option so that it runs in the background and you are not twiddling your thumbs waiting for thumbnail generation and actual run time is less important

Still doesn't explain why HD is so much slower than SD
 
Yes, preset at 38 seconds or first bookmark.
But I likes to be exact with the image!
So I let it run and then update it, unless its not going to be kept for a while.
 
I was curious so I did a small test.
Using WebIF/browse/OPT+/Set Thumbnail (on decrypted recordings)
  • SD thumbnails generating 5 previews took 8 seconds, use took 3 seconds
  • HD thumbnails generating 3 previews took 130-150 seconds, use took 35-60 seconds
So searching and using HD thumbnails is slow.

From the Queued tasks - previous tasks throughput
  • decrypt from 3.67 MiB/s to 8.62 MiB/s
  • shrink from 10.27 MiB/s to 18.65 MiB/s
By the way, I haven't installed the thumbnails package.
 
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SunnysideUK said:
OK, looks like 'normal' operation, for whatever reason.
Thanks for the reply.
Click to expand...
No problem at all, it's reassuring to know you're not alone..
While testing that I made identical recordings of Pointless on BBC1 SD and BBC1 HD to ensure similar samples. The times I gave earlier includes testing with new, old, similar and other recordings. The odd thing is that some BBC SD and HD recordings look similar in visual quality and the HD one is marginally smaller in size!
 
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Maybe it's recorded in StdDef bitrates and naturally broadcast over both StdDef and HiDef LCN's but HiDef will benefit from MP4 stream/file compression. Because it's a HiDef channel does not mean the source is HiDef, but mostly upscaled.
 
SunnysideUK said:
Maybe it's recorded in StdDef bitrates
Click to expand...
I can categorically assure you that this doesn't happen for proper TV channels, like the aforementioned, and probably not for anything else either.
Emission bitrates are not used for production.
 
Argh I made a rookie mistake. After I transferred the recordings to a laptop I see that the HD files are marginally larger. I think the HDR WebIF/Browse is reporting the wrong files sizes because the files have the same name.
 
SunnysideUK said:
Yes, preset at 38 seconds or first bookmark.
But I likes to be exact with the image!
So I let it run and then update it, unless its not going to be kept for a while.
Click to expand...
For HD recordings it might be quicker to Bookmark position for the thumbnail using the remote control while watching the programme on the TV!

Personally I keep so little that I just use whatever is generated and never bother to alter it
 
Understood.
That's what I usually do (if required), and just did for tonight's StdDef UFO episode.
On HiDef sometime even the bookmark is out when setting the thumbnail by 2 seconds or so, which is a big deal as it takes so long to load the images. Still no big deal.
 
I wonder if there's something wrong with the ffmpeg command for thumbnailing HD (=HiDef) recordings, such that it doesn't skip to the specified point but parses the entire stream. There is a known issue about positioning parameters to apply to the input file.

Or, is this why the on-box s/w makes the .nts file, and we should be using that to skip to the thumbnail position with HD recordings?

It would be good to confirm the issue with the latest 1.4.9-6 update.
 
/df said:
I wonder if there's something wrong with the ffmpeg command for thumbnailing HD (=HiDef) recordings, such that it doesn't skip to the specified point but parses the entire stream. There is a known issue about positioning parameters to apply to the input file.

Or, is this why the on-box s/w makes the .nts file, and we should be using that to skip to the thumbnail position with HD recordings?

It would be good to confirm the issue with the latest 1.4.9-6 update.
Click to expand...
It is not the skipping to position that is the problem - the time to create a thumbnail is the same at 5 seconds offset as a 50 minutes offset.

I don't remember the difference in creation time being quite as long in the past though I don't have any historic figures, I said ''a bit slower' in an earlier post - I don't think I would have called a minute 'a bit'
 
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