Changing bitrate & resolution (Mode 0) - Page 11

terryeden · 03-30-2005, 08:52 AM

Quote:

Originally Posted by blindlemon

Best: 7500000/9000000, Mode 0, RQ 100
High: 4800000/6000000, Mode 0, RQ 95
Med: 3660000/4800000, Mode 0, RQ 75
Basic: any old crap!

For basic, I found you can get down to 675000.
See my post http://www.tivocommunity.com/tivo-vb...d.php?t=222298

Perfect for recording on the radio - a 30 minute recording is around 172MB. So, 101 hours of Radio 4 on a 40GB TiVo.

Terry

sanderton · 03-30-2005, 09:25 AM

If you enable VBR, radio recordings plummet no matter what notional bitrates you put in.

ccwf · 03-30-2005, 09:45 PM

Quote:

Originally Posted by sanderton

Normal ones for Best. I didn't find the improvement for Mode 0 particularly noticeable with the "quality" of Sky input, and I have no problems with DVDs from Mode 4 video.

This is an important point. If the real resolution of the source signal is less than mode 4 resolution, then, by itself, using mode 0 instead of mode 4 yields no real improvement in quality. One is better off using mode 4 (or even lower resolution than that depending on the source) but increasing the bitrate.

That is what I myself have done. I performed Fourier transforms of signals from various channels to see how much horizontal resolution was really in them. Then I set up a range of modes for recording quality settings adequate to cover each of those source resolutions. Finally I increased bitrates.

gyre · 04-04-2005, 12:00 PM

Folks,

Am I right in thinking that changing 'high' to mode 0 and a 7500000 bitrate would give the same recording as changing 'best' to the same set of values?

i.e. a quality of 75 is the same as a quality of 100 as far as the resulting recording is concerned.

The reason I don't want to change 'best' is that I don't wish to get white flashing on live tv.

Thanks!

-- gyre --

bobones · 04-04-2005, 12:24 PM

Quote:

Originally Posted by gyre

Am I right in thinking that changing 'high' to mode 0 and a 7500000 bitrate would give the same recording as changing 'best' to the same set of values?
-- gyre --

Yes, but you may as well try VBR and save disk space as well as increasing resolution yet have enough bitrate headroom to avoid artifacts.

I use 9000000/4800000/mode0 on Best (100) and 7000000/3200000/mode0 on High (75) with excellent results. (My default recording mode is High, but live is viewed on Best).

Remember the filesize/disk usage will be related to the vbr figure, not the maxvbr figure.

bobones · 04-04-2005, 12:29 PM

Quote:

Originally Posted by ccwf

This is an important point. If the real resolution of the source signal is less than mode 4 resolution, then, by itself, using mode 0 instead of mode 4 yields no real improvement in quality. One is better off using mode 4 (or even lower resolution than that depending on the source) but increasing the bitrate.

The difference between mode0 and mode4 is very clear on my 43" display no matter the source. UK Freeview channels have a lot of widescreen output were the resolution does matter, but not only that, mode4 suffers from colour misconvergence that's not apparent in mode0. This is very clear with red text on a white background.

gyre · 04-04-2005, 12:29 PM

I will try VBR. Seems sensible if it works and doesn't give me artifacts nor lip sync problems.

My question was whether it made any difference if I changed the values for 'high' as opposed to 'best'. i.e. whether I'd see any difference in the recorded video quality. I think your answer is saying that I woudln't see a difference.

From the discussion above in the thread, it looks to me like you can have up to 2 sharp resolutions.

Thanks!

-- gyre --

bobones · 04-04-2005, 12:39 PM

Quote:

Originally Posted by gyre

I will try VBR. Seems sensible if it works and doesn't give me artifacts nor lip sync problems.

My question was whether it made any difference if I changed the values for 'high' as opposed to 'best'. i.e. whether I'd see any difference in the recorded video quality. I think your answer is saying that I woudln't see a difference.

From the discussion above in the thread, it looks to me like you can have up to 2 sharp resolutions.
-- gyre --

VBR doesn't affect the white flashing, which seems to happen whatever bitrates are used with mode 0. Lip sync can occasionally be a problem, but whether it's down to VBR, I don't know. Others have reported other artifacts with VBR but I have never noticed anything amiss myself.

This whole Record Quality thing is a red herring. Just keep the defaults and change the bitrates to whatever you want. I don't see why you can't assign high bitrates to medium and basic if you leave the RQ values as they were.

gyre · 04-04-2005, 12:47 PM

I've done mode 0 on 'basic'. It seemed blurred compared to what I'm getting on 'high'.

This might be a figment of my imagination, or it might be that only 2 modes are nice and sharp and the other 2 are blurry.

I'm willing to be proved wrong

-- gyre --

blindlemon · 04-04-2005, 02:16 PM

Quote:

Originally Posted by gyre

or it might be that only 2 modes are nice and sharp and the other 2 are blurry.

I used to think that the RQ in itself was what made the difference, but I am now convinced that it was indeed at least a pink herring as, regardless of RQ, you can only have 2 "sharp" qualities, and 2 slightly blurry ones.

It is possible to set "basic" to be one of the sharp ones, so long as you assign it one of the 2 highest RQ values out of the 4 allowed.

I agree with Bobones though, that a higher VBRbitrate will result in an improvement in PQ even in the 2 "blurry" qualities.

If you want to avoid flashes on Live TV then set the DefaultLiveRecordQuality to the same RQ as a quality that doesn't use Mode 0.

gyre · 04-04-2005, 02:27 PM

This all makes sense. Thanks you folks

-- gyre --

bobones · 04-04-2005, 07:08 PM

I now concur with blindlemon. The lower 2 RQ values are always slightly softer than the higher 2, no matter the values. It's as though the highest frequencies are filtered out on the 2 low RQ values. The real benefits of mode 0 will not be seen on anything other than the two higher RQs.

ccwf · 04-04-2005, 07:20 PM

Quote:

Originally Posted by bobones

The difference between mode0 and mode4 is very clear on my 43" display no matter the source. UK Freeview channels have a lot of widescreen output were the resolution does matter, but not only that, mode4 suffers from colour misconvergence that's not apparent in mode0. This is very clear with red text on a white background.

I've read about the colour convergence issue but have never seen it myself (it only seems to affect UK TiVo DVRs).

On Freeview, are you saying that all Freeview channels are high-resolution or that you only watch Freeview? Because if you use a plain old aerial instead of Freeview, then there should be no real benefit to mode 0.

bobones · 04-04-2005, 08:27 PM

Quote:

Originally Posted by ccwf

On Freeview, are you saying that all Freeview channels are high-resolution or that you only watch Freeview? Because if you use a plain old aerial instead of Freeview, then there should be no real benefit to mode 0.

I am saying that much of the programming on Freeview is high-res anamorphic widescreen where mode 0 offers noticeable improvements over mode 4. And, no I don't use the plain old aerial on my tivo at all, only freeview.

sanderton · 04-07-2005, 02:35 PM

Remember Freeview defaults to mode 2, not 4.

martinpw · 04-25-2005, 08:38 AM

I've changed by settings for best, and want to change them back, but I forgot what the original settings are!! can anyone help?

blindlemon · 04-25-2005, 08:44 AM

5960000/5960000, Mode 4 (mode 2 for CATV), RQ 100

mrhatken · 05-13-2005, 11:36 AM

Howdy All,

Thanks for this great thread! I'm an Aussie with a Thomson UK TivO that's working very well down-under (even though we don't have an official TiVo service here). But that's another story ...

I am writing here to ask a few questions about setting my TiVo to use Mode 0. I've read through this thread (and others) and made the changes suggested in LJ's Mode 0 page, with BoBones settings for 720 VBR (setup on the High slot).

The settings I used were:

CATVHighVBRBitrate 3660000 -> 4800000
CATVHighMABBitrate 3660000 -> 90000009
CATVHighResolution 2 -> 0

I made sure I hit enter when changing all the resources. I copied LJ's file to the TiVo in binary mode and replaced the original with the new file. I turned on "Save Disk Space" then rebooted. The TiVo crashed (rebooted) frequently for a while (6 times?).

It crashed when I was watching live TV (on Best settings). It crashed after a couple of minutes when I tried to record on the new 720 High settings. It crashed when I tried to watch previous recordings.

It has now stopped rebooting. I guess it has worked things out - flushed out any inconsistent settings somewhere (life TV buffer or whatever). So I am happy, but I am unsure if the image quality has improved.

I have a Standard Definition STB (free-to-air digital TV) that sends input to the TiVo using RGBS (SCART) and the TiVo sends its RGBS (SCART) signal to an LCD TV (1366x768) via a RGBS to Component converter.

My questions are:

1. How can I be sure that a recording is made on Mode 0 (720x568)? The recording says High (as configured) but I would like some secondary confirmation that it is Mode 0. I am using VBR so I don't think I would see huge files.

2. I set the DefaultLiveRecordQuality from 100 to 75, hoping that it would now make Live-TV work at Mode 0 (since 75 corresponded to the High settings). How can I confirm this? TiVo still suggests it is recording at Best. Is this possible?

Thanks in advance for any information and suggestions. If I can get this to work I will be one happy camper. Currently, on what I think is Mode 0, I am seeing no flashes and no artifacts.

It's a great picture but I would like to know for sure that it is not just the great picture we previously got on Best quality.

Cheers,
Ashley.

--
Ashley Aitken
Perth, Western Australia

blindlemon · 05-13-2005, 11:42 AM

If you look in the TVLOG just after changing channels on Live TV or starting a Mode 0 recording you should see a message with the phrase "using VBR, bitrate 4800000, maxBitrate 9000000".

If you see "using CBR, bitrate 5960000, maxBitrate 5960000" then you're not using Mode 0.

BTW, I assume your bitrate of 90000009 above was a typo?

mrhatken · 05-14-2005, 01:38 AM

Many thanks Blindlemon!

That tip helped me see that I wasn't even experiencing Mode 0 - I should have used DBS rather than CATV (I think).

Do others see a few crashes (3-4) after making changes? But then things settle down and I've had no problems since (no flashes yet, or lip sync problems).

And yes, that was a typo (but thanks for pointing it out).

Cheers,
Ashley.

LJ · 05-14-2005, 06:00 AM

Quote:

Originally Posted by mrhatken

Do others see a few crashes (3-4) after making changes? But then things settle down and I've had no problems since (no flashes yet, or lip sync problems).

I didn't get any reboots directly after changing mine. Usually my TiVo reboots are due to TiVoWeb searches producing too many results or, like yesterday, when I rebooted to enable the latest version of cachecard drivers.

davisa · 05-27-2005, 04:55 AM

Hi all.

Look, I don't normally do this, but after reading 11 pages worth of posts in this thread I'm totally confused and rather overwhelmed by so much information!

I've got Cable (Telewest) and want to try to improve the recording quality of TiVo from the default setup. I'm not bothered about mode 0 though as any sound slip or white flashes would drive me mad.

Can anyone suggest some sensisble settings to try to give a general improvement - particually for transferring on to DVD? I know many suggestions have been posted before - I just need a few pointers!

iankb · 05-27-2005, 06:17 AM

Do not assume that you will get white flashes and sound sync problems. I am using Mode-0 VBR with 'bobones settings', and this gives me DVD resolutions, 50% space saving, very, very rare white flashes, and no sound sync problems at all. It seems to depend on your hardware, as to what you will experience.

davisa · 05-27-2005, 08:02 AM

Quote:

Originally Posted by iankb

Do not assume that you will get white flashes and sound sync problems. I am using Mode-0 VBR with 'bobones settings', and this gives me DVD resolutions, 50% space saving, very, very rare white flashes, and no sound sync problems at all. It seems to depend on your hardware, as to what you will experience.

Thanks, I will dig out 'bobones settings' and give it a try.

I hated having to ask the question as I knew it had allready been answered so thanks for the reply.

swuk · 05-27-2005, 12:37 PM

I spent hours pouring through various threads to make sure I was doing the right thing. Like you, I'm using Telewest digital, and in the end I changed the DBSBest settings to mode 0, and upped the MaxRate to 9,000,000. (I think I changed the other rate as well, but I'm not at home now so can't check - sorry I'll check on this and edit over the w/e) And that was it. I left all the quality settings the same. I don't get lip sync issues nor white flashes.

tivo_boj · 05-27-2005, 05:20 PM

I changed to mode 0 4800000, 9000000 , and get more than flashes, I get some of the main picture flashing up at the bottom of the screen. Not usable at all. Left settings the same but changes to mode 4. all OK

What are the best non mode 0 setting for best, high. medium and basic?

blindlemon · 05-27-2005, 06:49 PM

I make most of my recordings at 3660000/6000000, Mode 0 and hardly ever get white flashes, so that might be worth a try.

Out of interest, what's your program source? Aerial, or BBC channels on freeview seem to be the worst for triggering white flashes, IME.

tivo_boj · 05-28-2005, 05:50 AM

Changed all the settings ( ie CATV, Aerial etc,)and was worse off freeview, but was not good for any. Even live TV ( which I beleive uses best) was bad.

I will try the lower settings, but it looks like my encoder/decoder is specfically bad as some of the High and Medium recording also showed the problem.

tivo_boj · 05-28-2005, 06:08 AM

Tried3660000/6000000, Mode 0, and looks OK from Sky, but freeview (RF) still have flickers every 5-10 secs, but much much better. BBC2 the worse followed by BBC1

What were the original settings for all 4 , as I may try then at Mode 0 and work back from there.

What about going for CBR for Best (ie Max. and min the same) mode 0 - would this improve things. Want the best Mode 0 setting so I can re-use the recording ( if you know what I mean)

davisa · 05-29-2005, 04:16 PM

Well I've done the deed and used the 'Bobones' settings for mode 0 and VBR. I set Top Gear on High (3200000-7000000 mode 0) and sat down to watch via component on my Sanyo projector projected onto a 7 foot glass bead screen - expecting a magnificent result the like of which I've never seen on TiVo before

Well, it looks absolutely terrible! Loads of MPEG artefacts and really severe colour banding

The old 'High' setting was 3660000 CBR mode 2. I just don't understand why that would be better- unless Top Gear was particularly badly filmed.

Anyway, set The Last Detective on 'Best' so i'll see if that's any better.

Confused to say the least.

(oh, didn't notice any white flashes or lip-sync issues)