Just noticed something that might be of interest to you:-

I had to use the free HDMI cable that came with the Humax because I ran out of good cables.

I have the Humax's Audio out to my amp connected by QED silver spiral cable.

The Humax is connected to the TV via freebie HDMI cable.

The picture is delayed compared to the sound when audio is via amp, but not when audio is through TV speakers.

If I put the QED HDMI cable in, the picture is not delayed any more compared to the amp sound.

Conclusion: cheap cables have too much resistance.
Picture quality is also noticably disgusting with cheapo.

I didn't realise the difference would be SO noticable.... maybe this is no surprise to you guys =)

It's an extremely surprising observation since the HDMI signal is in the digital domain and as such cannot be affected by cables in the way you describe.

Theoretically, if the cable was inadequately screened and there was an extremely electrically noisy environment there might be some kind of break up but it would be more akin to effects you get from a weak signal from the dish than the effects you describe.

Isn't there a degree of error correction like reading CD's ? I'm thinking if there was, this could slow down the processing.
and isn't the signal from the satellite also digital?

Indeed the QED cables have excellent screening... and with wireless Internet, mobile phones, cordless phones, among the other broadcast signals, RF remote control and a cabinet full of hifi equipment..... I'd expect there to be some noise =)
PS: I imagine signal travels more slowly over freebie cable compared to 99.9999999% oxygen free copper with silver plating, twisted and shielded ... at least that's what the QED's go on about =)))

You don't include error correction in situations where you can provide a clean signal.

Error correction is used for situations such as CD/DVD/mag disk /mag tape where the recording medium is not 100% reliable or where a signal is to be transmitted over a path that is not completely controllable such as any wireless transmission or long distance wired connections.

You don't use it where you can specify a wired connection that, if it working properly, can be guaranteed to be 100%. (e.g. all short distance local cabling).


Well, no, not as such, although it is an analogue of a digital signal - i.e. although the signal is analogue it is a representation of digital data. However if that signal is corrupted it will spoil the digital signal that is decoded from it so if your cable was inadequate you would see/hear the same effects rather than the ones you describe.


But the HDMI signal is designed to be sufficiently robust that it can be transmitted over normal cable without deteriorating to the extent that it would cause the digital signal to become corrupt.


IF there is any difference in the speed of transmission then it would be in the order of picoseconds (if even that long).

Certainly nothing you could detect.

I'm afraid that people selling these very expensive cables are charlatans.

The idea of special cables started in the Hi-Fi world many, many, years ago when people used bell-wire for their loud speaker connexions and in those circumstances you could improve the system performance by spending a little more money on some more substantial cable.

I understand what you've said.....
and it makes sense....

But.. there's a definite improvement between QED cables and cheap standard cables in hifi. If we're talking digital, then no idea. But analogue absolutely.
I have a CDP with 2 identical outputs and it doesn't matter which way round you cable it. Cheap cable that came with versus QED, amazing difference. The cheap one cuts off a lot of the range. Of course we're talking 11k GB pounds worth of Hi Fi equipment which is really sensitive and capable of frequencies that things on the High Street can only dream of.
I'm sure the cable set up on a "Stereo system" would make very little difference because it would all sound like cheap stereo anyway.

And the results with the HDMI...
If I put simultaneously the sound from the Hifi and the sound from the TV, big echo with cheap cable. Not so with QED cable. I'm curious what could cause that =)

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Yes, the electrical properties of a cable do affect an analogue signal.

However with digital, the signal is a series of 1's and 0's ( voltage and ground ) and is unaffected by cheap cables, provided the connections are sound. That being said, I am talking about cables of around 3m or less. Over that length, say, 10m or more, the electrical resistance of a cheapy cable could quench a 1's voltage sufficiently that it does not 'strike' components at the far end. In these situations, a more expensive cable is warranted.

Remember, if a true High Definition experience was dependent on top quality interconnects, then an expensive product like the HDR would ship with low oxygen, screened cable with gold plated connectors. That’d be another £50 please!

A lot of people will swear that expensive HDMI cables do improve their perceived enjoyment. Strangely, that level of commitment to these products is directly proportional to their investment in those products!! A little like the Emperor’s new clothes.

My advice, don’t be fooled by hype.

this is why high-end products don't ship rubbish cables =) they ship no cables at all.

I see your point about the emperors new clothes =D
But also, I can clearly see the difference in picture quality on my TV between the two cables. And why the sound delay then? =)

I think the cable is only 2 meters by the way, and the QED is 3 or 5, I can't remember which. Contrary to what you would think from the results.

I'm open minded about the digital all or nothing argument, but I've experienced different in reality.

Another example is that CD players do not all sound the same at all. Digital.

Ah, well. It was explained to me thus.... This is all because resolving the video image requires more processing power than audio. They went on.... If you use a high-end AV amp, you can delay the sound so that the video catches up.

Mind you, I suspect that the video’s delay in SD is not as great as it is in HD. If that is the case, then unless you tickle this adjustment with every channel change you are going to experience a little lip sync.

Maybe someone could qualify that theory?

The HDMI specification defines 4 levels of evolution, from version 1.0 to 1.4, (and version 1.2 introduced a facility called 'Auto lip sync' , but I do not know what this means!)

I wonder whether the HDMI cable supplied with the HUMAX tuner was only capable of supporting the minimum standard, but your more expensive cable was up to date. This could explain the difference found between the cables, if the tuner and TV expected to coordinate their signal processing.

I too have found that the HUMAX tuner ouputs audio 200mseconds ahead of the displayed video . But I am using the supplied HUMAX hdmi cable, AND when I switch on the TV it gives an error report saying that the audio input is incompatable. The TV is new, and maybe expecting a better source. So maybe it would be worth buying a reasonable , up to date, HDMI cable, which supports v1.3.

I think I may be suffering from a similar problem - sound on BBC/ITV HD channels is slightly late when played through my LG 42LH5000's speakers, but if I plug a normal hifi into the phono outs on my Humax Foxsat PVR, then the sound from the hifi is perfectly in sync.

I too am using the cheap HDMI cable supplied with the Humax. AIUI, the lip sync functionality was added in HDMI 1.3. Questions I have:
[LIST=1][*]My TV supports HDMI 1.3, does the Humax?[*]Does a cable also need to support the 1.3 spec or will any cable do?[*]If the cable needs to be 1.3 spec too, is the cheap cable that comes with the Humax compatible with the 1.3 spec?[/LIST]
My hunch is that it's the cheap cable - in general Humax lip sync problems were resolved a while ago and were partly the Humax's fault, partly the broadcasters' - the fact is the HD broadcasts are perfectly audio-synced when the sound goes out of the Humax's phonos.

I've read elsewhere that say that cheap cable cannot be the cause of these problems, but, I have seen cables that claim to meet the HDMI 1.3 standard, and I wonder whether the cable that came with the Humax does or does not. Perhaps if the cable doesn't support it, the TV and the Humax aren't able to negotiate the lip sync delay or something, and that is the reason it's not quite right.

Thanks in advance for any advice/answers/etc!

Rich

The Humax HD does not support auto lipsync. It uses 1.2a. Got that direct from their tech support manager. I would say this is the same for the HDR.

The cable should have no effect on sync. Any cable (over a short run) will do, I have tried loads from VERY cheap to expensive. Long runs may require better cabling.

Have you accurately assessed the sync with the BBCHD test card?

See here to find out how.

http://www.bbc.co.uk/blogs/bbcintern...rom_the_h.html

Since the BBC and humax sorted their respectives problems (about a year now) BBCHD has had consitently accurate sync.

I measured it at 5ms through my AV amp and 15 ms through the plasma. see post 124 in Andys blog.

Have you checked the lip sync adjustment in the Humax menu? From what you describe this may not be at zero.

If it is set to zero I would expect when plugged into your TV the sound to be in sync.

When plugged into your amp I would expect the sound to be ahead of the picture.

The reason for this is the plasma / LCD perform video processing which take a finite amount of time, typically 40-120ms. The TV knows this and should delay the audio appropriately. Your stereo amp doesn't know this.

Proper AV amps have a feature where you can delay the audio.

The humax has the lipsync setting to acount for the situation that you describe with a normal stereo amp and for TVs that don't work properly!

Just a point about cables.

Resistance in cables or poor quality cables will not cause any delay which would be observable by a human, maybe poor quality cables might cause picture drop outs, or add noise or colour the sound from the source to the amp, but it wouldn't cause a noticeable delay.


The most likely cause for the delay is the time taken for the tv to process the digitised audio/video stream, meaning the audio feed from the amp isn't going through this process and hence does not suffer a delay. I have to say, I do not get this delay myself so I suspect it's down to the tv.

Hi

Thanks for the replies!

I have already used the BBC's test card, and, as far as I can see, the sound is accurately playing on the centre point - the lip sync problems only appear when the TV is displaying a more complicated image. I have no idea whether the relatively simple lip-sync-test image takes less time to process than a more natural image (such as scenes from the recent costume drama Emma, where lip sync is definitely a problem).

My question about the cable was not to do with resistance but to do with whether the cheaper cables supported the more advanced features of HDMI such as the lip sync functionality in 1.3. It sounds like even if the cable did support this, the video source doesn't.

I have tried all sorts of options with the Humax's delay settings, and have got nowhere - when it is set to zero, the sound is still late - I need to bring the sound forward.

As you say, if it's not the cable, it sounds like it is the TV , which is a shame :S

One final point, if I pause the recorded programme on the Humax, the sound on the HiFi stops immediately, whereas on the TV it takes a second or two to stop - perhaps this is normal behaviour for HDMI (sound sent in chunks) but maybe this is more a problem with the delay being introduced somewhere?

Thanks again for the replies

Rich

The complexity of the image will make no difference to the sync, so if the testcard is in sync then any programs should be too, unless there was a specific broadcast problem with a program.

This does happen from time to time, there have been drop outs on some recent BBCHD programs, but you usually see others complaining on the forums about it which I havent seen.

So, overall I am a bit confused. Scrub that...... very confused!

Seeing as I have seen no one complaining about sync lately I would suggest that the broadcast is OK and the humax is working correctly over HDMI. It is certainly fine here.

So that does suggest your TV is a fault.

However that does not expalin you saying that testcard is in sync and programs are not.

I would suggest you stick the HUmax at zero delay and check the testcard again (sound through hdmi to tv).

This should be in sync. If it is then check a number of programs on BBCHD. Make a note if they are stereo or 5.1. It is highly unlikely this should make a difference, but it's worth checking.

One last thing, can you confirm you are not connecting the analogue audio phonos to your TV and that there is not a scart lead from the humax to the TV.

Also ignore the hifi amp for the moment, lets just establish what the TV is doing.

Hi

Thanks for the reply - I'm going to see if I try a few things out tonight.

One thing I'm going to try is a factory reset of the TV - perhaps I've got something wrong on there.

I will be in touch!

Cheers

Rich

That's normal

Ok, I have done a factory reset of the TV, have verified the Lip Sync on the Humax is set to zero, and then checked the (recorded) Lip Sync test broadcast from BBC HD, and this time I have paid a bit more attention.

It is very close, and hard to tell how late it is, but the sound is definitely a little late. It is hard to say how late, but it is either at the 1 or 2 to the right of the centre (it's definitely not before the centre).

The only other thing I've noticed is that on the BBC Test Card (the one with the girl and clown) the "Rs" sound test is corrupted. Perhaps that's normal in traditional stereo?

There is SCART plugged into the TV from another STB, but no SCART coming from the Humax.

Looks like it's the TV

Rich
ps: I have turned off the Simplink function on the TV (it's an LG) as this has fixed the problem in other LG TVs, but this has made no difference with my model.

Unfortunately, considering that I havent seen anyone else on the forums currently complianing about sync, and havent for some considerable time, it really does look like a problem with your TV.

The only other thing I would do is perform a factory reset on the humax just in case.

Regarding the Rs sound you should hear all tones clearly, except the LFE sub if a stereo mixdown is being performed.

The only other thing you could possibly do is plug another TV into the Humax, or take the Humax to friends if they have sky or freesat and try it on their TV. Just to make absolutely sure!

I have seen one other person complaining about lip sync on my specific model of TV with Freesat (no idea if it's a PVR he's using), so it's either the TV, or, if this is possible, the combination of TV and STB.

Thanks for your help!

There is image processing in the TV and audio processing in both devices (TV and STB), it is the job of each device to ensure the delays introduced by each stage are correctly compensated for before output.

A great deal of effort goes into many new TVs to improve the picture quality with features like 100Hz, naturally these require time for the signal processors to process and thus there is some natural delay which must be accounted for by adjusting the timing of the output of the device. I wouldn't want to point the finger especially at any one manufacturer but on some products I have seen some interesting motion interpolation which causes temporal distortion in motion.

However, also note that the specifications for MPEG do not require Audio and Video to be in sync at all times. During times of high motion it is possible that the movement on the screen may not correlate with that of the audio. This is most notable on some low bitrate music channels with high-action and frequent cuts. This could be a reason why video and audio occasionally seems out of sync?

A great deal of time has been spent at Humax on lip-sync and we continue to study it at each stage. I don't believe we have an issue with the HDMI output currently.

Hi Bob_Cat

Thanks for getting back to me!

I don't think it's a Humax issue - I'm pretty sure it's the TV (LG 42LH5000). It happens to a greater or lesser extent with all HD broadcasts on BBCHD/ITVHD (I have not tried Lux, nor do I have another HD source such as BluRay to compare with) - perhaps it's normal, but, as you say the industry has put a lot of effort into lip sync, and, speaking as a consumer, I'd hope they'd have got it right by now!

The only thing I've not tried yet is moving on to another firmware on the TV, I think that's the next thing to try.

Thanks again

Rich