User Thumbnail Generation Fails

[escat]

af123's Thumbnail Generation feature of the web interface is a really useful feature*. But I find it often fails on a particular class of recordings: specifically, programmes originally transmitted, say, twenty years or more ago and now retransmitted on, say, the Drama or ITV3 channels: Morse, Poirot etc.

In these situations, whether I use the book-mark technique or simply set my own timer in the "Set Thumbnail" panel, I am simply offered a choice of five grey boxes. Yes: I have decrypted the recordings first; and yes: it occurs on more than one Humax box.

My supposition - from fiddling with recordings to find out what triggers the problem - is that it is somehow connected with the fact that these programmes were made in the pre-wide screen era, and have not subsequently been 'remastered'. I do notice, however, that the default thumbnail generator works OK, even when the web-interface one does not. One other 'clue': If I strip off all the modern lead-in to the old recording, then the web interface routine seems to be able to cope with what's left.

Any ideas, anyone?

Thanks

(*I'm not trying to re-open the "Why do you need thumbnails?" debate. Suffice it to say that my three-year old grand-children find it an invaluable way of selecting Peppa Pig or Thomas the Tank Engine.)

 

[MontysEvilTwin]

I have a work around. Play the recording and stop just before the point you would like to use as a thumbnail. Use a file explorer or FTP to delete the existing thumbnail. If you then resume play it will create a thumbnail based on where you restarted playback.

 

[Black Hole]

My supposition - from fiddling with recordings to find out what triggers the problem - is that it is somehow connected with the fact that these programmes were made in the pre-wide screen era, and have not subsequently been 'remastered'. I do notice, however, that the default thumbnail generator works OK, even when the web-interface one does not. One other 'clue': If I strip off all the modern lead-in to the old recording, then the web interface routine seems to be able to cope with what's left.

Any ideas, anyone?

Plenty, thanks to your analysis. It looks like the ffmpeg process used to parse the video file through to the marker for the thumbnail gets confused by the format switching.

 

[escat]

I have a work around. Play the recording and stop just before the point you would like to use as a thumbnail. Use a file explorer or FTP to delete the existing thumbnail. If you then resume play it will create a thumbnail based on where you restarted playback.

Brilliant! Thanks. I kick myself for not thinking of this. I had noticed that, if I used the web-interface program to set a bookmark in the middle of the (modern) adverts - as opposed to the middle of the (old) progamme - then it was quite happy. Together with your work around, this suggests that the default thumbnail generator may be looking at the local context to determine the frame format, whilst the user thumbnail generator may be looking at the start of the recording?

Thanks again.

 

[MontysEvilTwin]

Brilliant! Thanks. I kick myself for not thinking of this. I had noticed that, if I used the web-interface program to set a bookmark in the middle of the (modern) adverts - as opposed to the middle of the (old) progamme - then it was quite happy. Together with your work around, this suggests that the default thumbnail generator may be looking at the local context to determine the frame format, whilst the user thumbnail generator may be looking at the start of the recording?

Thanks again.

I think Black Hole (post #3) is right about the custom firmware thumbnail generation problem. The HDR-FOX just uses its own proprietary software which is unaffected by the video format change.

 

[MymsMan]

It could be a useful addition to Sweeper if it provided options for setting the thumbnail image either as a time offset from the start of the recording or from an external image file.
e,g.

thumbimg=/mod/img/peppapig.png
or
thumboffset = 30s

 

[jxp]

The last post in my thumbnails thread http://hummy.tv/forum/posts/43892/
has a script for doing just that.

If I ever had a any spare time I was going to try and wrap it up as a package.
All the settings are at the top

• targetTime = seconds from the start to capture a frsame
• slowForSD = 0 (off) or 1 (on) to use a slower fallback method for SD files for the problem you found. (HD files would be too slow for this approach)
• fallbackTarget = seconds from the start if you get a problem thumbnail and not using slowForSD
• logActionsOnly = 0 (off) or 1 (on). Controls how much is written to thumbnails.log

I use this all the time, and it generally gives me thumbnails that obviously relate to the recorded program.