Last nights Tomb Raider on BBC HD was held at the start and we started watching in "time slip" mode (sounds good though ) but after a few minutes the picture kept freezing and changing to a different "still" image every 20-30 seconds or so, although the audio was coming through fine, finally I had to revert to "live" mode to view the film.

My hard disc is only about 48% full......

Never happened before, anyone seen this?

Yes, this happened here too. I was recording it in non-freesat mode & watched the first few minutes. Did it behave itself after that?

Yes once I had reverted to "live" mode there were no problems.

It was almost as if the hard drive could not keep up with the task of writing and reading all the information in HD at the same time.

If this is the case, and it was a HDR issue perhaps its an issue for Humax as the Humax encoder obviously couldn't cope with the encoding the BBC broadcast encoder was feeding it with.

Maybe a software update needed?

Any comment Bob_Cat?

Does the HDR not record the encoded stream to the HD?

Even at 32Mb/s it would only be 4MB/s to write and read to the HD which is trivial even for a relatively slow HD.

Didn't see the film but did catch the last 5 mins on BBC HD and it was immediately followed by an announcement apologising for "problems with the picture on the HD channel" - so I assume the problem was at the broadcasters end.

I watched the first five or so minutes and saw some freezing effects. I was also recording it at the time. I think it was simply a transmission glitch.

One of the tests I did when I upgraded my Humax hard drive was to simultaneously record two HD broadcasts (ITV HD and BBC HD) whilst replaying a BBC HD recording. No problems seen. This was done before the BBC and ITV dropped their bitrates so would be more demanding than the same test repeated today. The recordings and playback were fine no glitches or problems seen. My disc is a Western Digital WD10EADS and it is not quite as fast as some discs as it is a low power version.

Most modern PVR compatible discs are specified as able to cope with 10-12 simultaneous HD recordings at once – just a case of the controller/processor keeping up.

Question is does it decode it 1st?

I'm not sure of the answer to that but its strange if people who watched it live had no problems but those who recorded it had time slip issues.

I'm pretty sure it doesn't.

If it did it would:

a) Treble the processing power required if someone was recording two channels and happened to be able to watch a third channel.

b) Mean that it would require vastly more space to store the decoded stream on the HD.


Strange unless there's some kind of bug in the Humax that has been triggered by the new encoder that BBC is using. (I'm assuming that the encoder is not at fault as people watching it live were OK but that may well be a dangerous assumtion.)

If it decoded it first the file size would be massively increased as you would have 25 full frame images for 1 second of video. In mpeg2/4 there is one full frame followed by a series of difference only info. The maths is pretty simple a 1920 x 1080 image using 8 bits per colour (24 bits in all ). Thats 1920 x 1080 x 25 x 25 bits/sec. = 155520000
bytes/sec. For 1 hr of video thats 155520000 * 60/1024 = 9331200000 bytes approx 930Gb. A ITb drive won't go very far .

I hope I got the maths right

Bits per second = 1920 * 1080 * 25 * 24 = 1,244,160,000

Divide by 8 for bytes per second = 155,520,000

Multiply by 3600 for an hour = 559,872,000,000

Divide by 1e9 for gigabytes = 560

(I think that's right but I wouldn't stake money on it! )

Which is not quite a two hour film on a 1TB drive (although as it's interlaced if you took that into account you'd only need 280GB per hour).

You wouldn't store it in RGB, you'd store it in YUV, which is effectively 12 bits per pixel.

It's still a massive storage requirement but fascinating nevertheless

oh good .. it wasn't just mine then !!

I was watching live and had all the freezing you've been discussing

Just to confirm it wasn't a Humax problem.

I had it on Sky. And I wasn't time-shifting. I was watching live.

Same here. Picture was all over the place.

So it was at the BBC's end then. Sounded a little strange but when someone reports trouble free live viewing you have to assume it was at the Humax end.

Anyway, I junked my recording. The freezing and the fact that it wasn't very sharp made it not worth watching in my book. I'm allergic to unsharp HD !

T'was me who reported that, then I assume that I switched to live mode just as the BBC problems were getting sorted, I think it was about 10 miuntes or so into the film that it ran OK from......