Monday, 30 July 2012

Day 6 - Still a packed schedule

Today is only a fractionally less busy day than yesterday with all 24 channels used again, 23 sports involved and 58 recording slots totalling 220 hours and 40 minutes. Apart from missing channel 24's events completely, the other interesting note is that the BBC has finally decided to experiment with splitting up some of the tennis slots into two, which is something I've been banging on about for days now.

Channels 22 and 24 will broadcast tennis in 11:30-16:00 and 16:00 to 20:10 slots, which is great, but sadly the mad 8+ hour tennis slots remain on channels 6 and 7 (I will be splitting those along with sailing, which is still over 6 hours today). The BBC have also finally mostly split each football match onto separate channels, though channel 4 wrecks it with a 2-match 5 hours 5 mins slot at 14:20. So better scheduling from the BBC at last, but by no means perfect.

It's slightly worrying that Team GB have no gold medal yet and languish 16th in the medals table after 5 days of events. We were far too optimistic about Cavendish for road racing gold the other day, IMHO. If anyone's seen the Tour De France over the years, they'll know it's an unpredictable sport, particularly if a strong breakaway occurs.

Also, I was surprised how all the British riders behaved like they were a team and didn't have anyone try to join the breakaways - it was an individual event after all (there are no team prizes or glory like in the TDF). As an individual rider, Cav's complaints about other teams not working shows the wrong attitude - it was every man for himself (the winner wasn't working with anyone!) and this was the flaw in all the British riders' tactics.

A couple of times today, the Now/Next info has actually managed to double up recordings in tvheadend for the same satellite channel! Something seems to pick up an empty slot title (e.g. "This is BBC Olympics 9 HD") and put it into the current active recording slot and, somewhat bizarrely, also records it despite it not matching any of my Automatic Recording strings (I deliberately made sure that empty slot title didn't match, otherwise I would end up with thousands of  hours of timetable video :-) Luckily, the original recording in that slot continues as well and I just leave both running unless there's SSD space issues.

I just realised I didn't show some of the output from the script I wrote the other day to keep an eye on the recordings from a filestore point of view. It was mainly written to make sure that what was on the tvheadend Web interface matches what's on the filestore. So here's an example from today (I have the script on both pc1 and pc2):

  4992 MB: BBC-Olympics-2-HD/-Olympic-Gymnastics-Artistic-.mkv
18320 MB: BBC-Olympics-4-HD/-Olympic-Tennis--1.mkv
11843 MB: BBC-Olympics-5-HD/-Olympic-Tennis--1.mkv
 9616 MB: BBC-Olympics-6-HD/-Olympic-Sailing--1.mkv
21932 MB: BBC-Olympics-8-HD/-Olympic-Hockey-.mkv
 8242 MB: BBC-Olympics-12-HD/-Olympic-Weightlifting-.mkv
 4877 MB: BBC-Olympics-13-HD/-Olympic-Basketball-.mkv
16437 MB: BBC-Olympics-14-HD/-Olympic-Beach-Volleyball-.mkv
 9908 MB: BBC-Olympics-15-HD/-Olympic-Archery-.mkv
 6137 MB: BBC-Olympics-20-HD/-Olympic-Table-Tennis-.mkv
 7327 MB: BBC-Olympics-21-HD/-Olympic-Tennis--1.mkv
13610 MB: BBC-Olympics-23-HD/-Olympic-Boxing-.mkv
Active: 12, total: 133247 MB (130.1 GB), free: 32050 MB (31.3 GB) = 16.32%
16675 MB: BBC-Olympics-19-HD/-Olympic-Badminton-.mkv
Done: 1, total: 16675 MB (16.3 GB), free: 32050 MB (31.3 GB) = 16.32%

Any filename with "--1" in it is a second file that is recording after a split (i.e. I split Tennis and Sailing today). The first file will already have been moved to HDD of course. You can see a 16GB Badminton file that would be moved to HDD a few minutes later by my transmedia program, which freed up that space on the SSD. If anything appears in the Done list that shouldn't, then I'll know something is wrong.

One handy thing to do is to keep a rolling set of 2 runs of the script output in the terminal permanently, so you can compare between runs and see what's changed. I tend to run the script when multiple recordings start simultaneously (which unfortunately happen a lot!), to make sure things look OK.

On another note, I've been running a BBC One HD feed in XBMC permanently during the day (switching it occasionally to a sat feed when the BBC One HD sport is boring). Prior to today, I'd only put it on occasionally if there was really something important to watch.

A little sad to see that after 6 days of events and the awarding of 38 gold medals, Great Britain has failed to win a gold and has slipped even further to 20th in the medal table. Let's hope that we climb up the table soon! An impressive start by France I see - thanks to their swimmers, they've got 3 golds and lie in third place in the table.

  Day 6 recording size: 1104GB - grand total so far: 4077GB (4.0TB)


  1. I have really enjoyed reading your blog over the last few weeks and have found it interesting and informative. It is nice to know someone else shares my interest. I am recording a fair amount of the Olympics on a more modest system. I have one PC with 6TB and a TBS dual DVB-T2 tuner plus a TBS dual DVB-S2 tuner connected to a dual LNB dish. I am using NPVR software on my PC.

    I had a major issue this moring at 9.50am when the scheduled recording of the Swimming Heats was supposed to start. It caused my recording of the Rowing Heats and BBC One HD to stop and I was unable to get it to start. It took over an hour and half and a re-install of NPVR to get my system up and running again. I was extremly dissappointed to miss the Swimming and Rowing Heats on the 24 Streams and BBC One HD's coverage between 9.50 and 11.40. Have you had any missed recordings? I was wondering if after the games are over whether you would be willing to allow me to get a copy of the coverage I missed from your recordings. I would be willing to cover any expense that this would require. Also even though it may be very unlikely, if you miss a recording and I happen to have it I could help you out.

    Thanks and good luck.

  2. I must confess I haven't been checking all the live streams or recordings - it's just impossible to keep an eye on all 30-odd channels of video. Each morning before the first recordings, I just whizz through a few terrestrial and 6 satellite channels (BBC Olympics 1-6 HD cover the 6 transponders).
    Once or twice, I've had to reboot before the first recording of the day because the tuner drivers didn't initialise properly, but once they're going, they're fine.

    I will be stung badly if sports overrun and the Now/Next (EIT) system doesn't adjust for this. It's even worse for terrestrial recordings which I'm using XML TV and EIT and I'm not sure which one has priority! I have noticed the odd issue with Now/Next and have ended up additionally recording one of the timetable video channels on satellite when the info flicked before the end of its slot!

    The Opening Ceremony (21 mins overrun) and the North Korean football flag incident (60 mins overrun) are the ones I know of and I luckily surfed the BBC Website for the latter to discover the hold-up, but there could have been others. So if things are on schedule, I'll have them recorded - both terrestrially and satellite - but if they overrun by more than 5 minutes, I won't.

    So the upshot is that I could have missed some stuff, but I won't be reviewing it until after the Olympics. Being forced to split long recordings into two to avoid filling the SSD loses out under 5 seconds of video. Clearly, I'll have lot of video editing post-Olympics!

    Anyway, looking at your request and at my HDD filestore, I see the following:

    Rowing - 14.5GB - BBC Olympics 2 HD
    Swimming - 9.5GB - BBC Olympics 1 HD

    I also have recordings of BBC One (SD) and BBC One HD for the morning session. I haven't looked any of these though, so they could be pristine or messed up...

  3. I am glad that your recordings have been going well. I know that sometimes the victory ceremonies can over-run so that is someting I keep an eye on.

    Something I have noticed with my system is that I get quite a few signal breaks that last around a second when I watch them back. These appear as a kind of blocking. I am used to recording SD and usually run my recordings through VideoReDo to edit them and also to make sure audio doesn't go out of sync. With SD VideoReDo can usually handle the signal break and save the video. However with HD it seems to get stuck at the point that the signal went for a very brief moment, so I have to go and look for any points that the signal went and manually edit them out. This is quite time consuming so I will do it after the games.

    Out of interest do you think satellite HD or terrestrail HD is better. Just comparing BBC HD and BBC One HD I believe on satellite it is a fixed bitrate of 9Mbps and is always 1080i and on terrestrial it is a variable bitrate that averages around 7.8Mps and can sometimes be 1080p, like during the highlights show. I also wonder if they use different encoders for satellite compared to terrestrial. Audio as well is AC3 fixed bitrate on satellite and AAC variable on terrestrial.

    Finally with regards to the recordings I missed yesterday I would love to get a copy of them if you would be willing. I can wait until after the games and if have a prefered method as to how I could get a copy of them please let me know.

  4. The BBC do indeed seem to encode differently on satellite to terrestrial, plus have you noticed that the BBC terrestrial HD channels actually switch encoding when they hit the break inbetween programmes? That doesn't happen on the satellite HD channels, so quite why they do it on terrestrial HD is beyond me.

    I also don't fully trust HD to work all the time (witness Andy Murray's Wimbledon quarter-final going AWOL on all BBC HD channels on all platforms for 20-odd minutes and yet SD carried on without any interruption!). It's why I record both BBC One and BBC One HD to play it safe.

    As for the glitches you mention, I have seen them on the odd occasion on satellite HD recordings, but not on terrestrial HD recordings. I'm not sure if it happens on the occasional key frame - it's often when the camera is about to change to another completely different shot (which is why I mentioned key frames).

    I'm wondering if, say, all 4 HD channels on one transponder have a key frame at the same time, the amount of data needed to transmit exceeds the bandwidth needed on the transponder so perhaps some of the key frame data gets dropped? It's only a theory - you'd have to prove it with multiple different recording systems and see if they all glitched at the same time.

    As for copies of the recordings, technically that might actually be illegal :-) Not that it ever stopped anyone before! I would have to review the recordings after the Olympics and see if they are in a decent state (they should be unless they overran as I've said).

  5. Out of interest do you recieve terrestrial from Crystal Palace. I do and and for HD on my TV it says the signal strength and quality are both 100% and when watching live on the TV I don't notice any signal loss. I have always wondered why with good signal I get these glitches on the PC. These terrestrial glitches go back through 4 DVB-T tuners and 2 PCs plus 1 Laptop over the last 8 years. As whatever hardware or software I have used over the years has not stopped these glitches, and my signal strength is good, I have just assumed it was a general problem when using TV cards in PCs and have got used to it. It would be so much easier if I didn't have this issue, but it would require someone with far more knowledge then me to figure out why it happens.

  6. The spec on the PCs I'm using are pretty high (lots of RAM, very fast SSD, i7 2600 CPU, TBS twin and quad tuner cards), so I don't think I'm lacking on the hardware side. When the tuner drivers are all up and running OK, I get 100% quality pretty well all the time on tvheadend's monitoring, plus the aerial/satellite installer said I had good signal strength using 5 grand of monitoring kit apparently.

    Having said all that, I too occasionally see a glitch when watching live, but I have been recording my normal TV schedule exclusively on satellite as a pre-Olympics test and playing back those recordings fully seemed to be OK. And, yes, all 8 tuners were working perfectly in the month leading up to the Olympics - my tests even ramped up to 18 HD channels on one PC simultaneously without a problem. It's why I was gutted to start the Olympics with less than 8 tuners and have just about limped along OK with 7.

    Assuming my satellite and aerial setups are OK, my suspicion about any glitches is either the low-level tuner drivers (I build those from source downloaded from the TBS Website) or possibly tvheadend's use of those drivers. Either way, it feels like a software issue than a hardware one, but exactly where that issue is located isn't clear to me.