Re: Recording HD vs SD signal

[·´¯`·.¸¸.·´¯`Dingbat·´¯`·.¸¸.·´¯`]

"georgiarose" <georgiarose@nospam.com> wrote in message
news:424d44ba$0$5399$afc38c87@news.optusnet.com.au ...
> This may be a dumb question, but I'm wondering if I want to record a
> program which is broadcast in both HD and SD, will the recording be any
> better or worse if recording the HD or SD signal. I've got component in
> from the HD-STB to the DVD recorder and obviously the recorder cannot
> record the HD signal, but will the recording be worse if it is effectively
> downconverting the HD signal as opposed to just recording the SD signal?
> Thanks in advance.

The end result will be exactly the same.

DVD Recoders record at a resolution of 720 x 576

This is exactly the same resolution as SDTV broadcasts.

So in theory the recording will be an exact match of the broadcast.

If you record from HD transmassion it will only be recorded at the the DVD
Recorders max resolution anyway.

[Lord-Data]

It can vary a little tho .. Some boxes can mess up the downsampling a little
... ie, it has to do extra work, and often the downsampled HD->SD can be
worse than the straight SD .. but, in some cases, and it depends on the box
and how it works, i've seen times where due to the limited bandwidth, the SD
signal drops quality a little bit .. especially high motion scenes, where
the HD stream seems to capture it a little better .. downsampling this, on a
box that can manage it properly, tends to give a better quality .. but it
all depends on your box, and how it handles it..

--
--
[ VIDGuide.com ] [ Irdeto Card Sharing Resources & Other Sat TV Interests ]
[ http://www.VIDGuide.com ]


"·´¯`·.¸¸.·´¯`Dingbat·´¯`·.¸¸.·´¯`" <spam@optusnet.com.au> wrote in message
news:424daf61$1@duster.adelaide.on.net...
>
> "georgiarose" <georgiarose@nospam.com> wrote in message
> news:424d44ba$0$5399$afc38c87@news.optusnet.com.au ...
>> This may be a dumb question, but I'm wondering if I want to record a
>> program which is broadcast in both HD and SD, will the recording be any
>> better or worse if recording the HD or SD signal. I've got component in
>> from the HD-STB to the DVD recorder and obviously the recorder cannot
>> record the HD signal, but will the recording be worse if it is
>> effectively downconverting the HD signal as opposed to just recording the
>> SD signal? Thanks in advance.
>
> The end result will be exactly the same.
>
> DVD Recoders record at a resolution of 720 x 576
>
> This is exactly the same resolution as SDTV broadcasts.
>
> So in theory the recording will be an exact match of the broadcast.
>
> If you record from HD transmassion it will only be recorded at the the DVD
> Recorders max resolution anyway.
>

[georgiarose]

"Lord-Data" <data@ihug.com.au> wrote in message
news:424db4e9$0$27856$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au...
> It can vary a little tho .. Some boxes can mess up the downsampling a
> little .. ie, it has to do extra work, and often the downsampled HD->SD
> can be worse than the straight SD .. but, in some cases, and it depends on
> the box and how it works, i've seen times where due to the limited
> bandwidth, the SD signal drops quality a little bit .. especially high
> motion scenes, where the HD stream seems to capture it a little better ..
> downsampling this, on a box that can manage it properly, tends to give a
> better quality .. but it all depends on your box, and how it handles it..
>
> --
> --
> [ VIDGuide.com ] [ Irdeto Card Sharing Resources & Other Sat TV
> Interests ] [ http://www.VIDGuide.com ]
>
>
> "·´¯`·.¸¸.·´¯`Dingbat·´¯`·.¸¸.·´¯`" <spam@optusnet.com.au> wrote in
> message news:424daf61$1@duster.adelaide.on.net...
>>
>> "georgiarose" <georgiarose@nospam.com> wrote in message
>> news:424d44ba$0$5399$afc38c87@news.optusnet.com.au ...
>>> This may be a dumb question, but I'm wondering if I want to record a
>>> program which is broadcast in both HD and SD, will the recording be any
>>> better or worse if recording the HD or SD signal. I've got component in
>>> from the HD-STB to the DVD recorder and obviously the recorder cannot
>>> record the HD signal, but will the recording be worse if it is
>>> effectively downconverting the HD signal as opposed to just recording
>>> the SD signal? Thanks in advance.
>>
>> The end result will be exactly the same.
>>
>> DVD Recoders record at a resolution of 720 x 576
>>
>> This is exactly the same resolution as SDTV broadcasts.
>>
>> So in theory the recording will be an exact match of the broadcast.
>>
>> If you record from HD transmassion it will only be recorded at the the
>> DVD Recorders max resolution anyway.
>>
>
>

This is what I was thinking may potentially happen. I have the Teac box but
haven't really tested recording that much stuff as yet. Thought someone may
know. Cheers.

[Stephen Neal]

"·´¯`·.¸¸.·´¯`Dingbat·´¯`·.¸¸.·´¯`" <spam@optusnet.com.au> wrote in message
news:424daf61$1@duster.adelaide.on.net...
>
> "georgiarose" <georgiarose@nospam.com> wrote in message
> news:424d44ba$0$5399$afc38c87@news.optusnet.com.au ...
>> This may be a dumb question, but I'm wondering if I want to record a
>> program which is broadcast in both HD and SD, will the recording be any
>> better or worse if recording the HD or SD signal. I've got component in
>> from the HD-STB to the DVD recorder and obviously the recorder cannot
>> record the HD signal, but will the recording be worse if it is
>> effectively downconverting the HD signal as opposed to just recording the
>> SD signal? Thanks in advance.
>
> The end result will be exactly the same.

Surely it will be similar - but not exactly the same.

Assuming the programme source is HD - so 1920x1080 (or 1440x1080).

Then if you record the SD broadcast then you will benefit from a broadcast
quality standards conversion from 1080/50i to 576/50i - performed using a
reasonably expensive converter, with some pretty sophisticated image
processing to deliver decent quality results.

If you record the HD broadcast via a domestic set top box downconversion,
then you are at the mercy of your set-top boxes scaling and conversion
algorithms, which may not be as good.

So from this angle, the SD source may be better.

HOWEVER - you also have the different MPEG2 distribution to take into
account. The HD and SD broadcasts could be of different qualities.

If the SD version is highly compressed - then any advantages resulting from
a broadcast quality converter may be offset by excessive compression
artefacts - which will be at the SD level (so quite coarse).

If the set top box downconvered HD signal is recorded, then the MPEG2
compression artefacts will be present at the HD, not coarser SD, level, and
when downconverted may well be less visible (as the extreme HF noise
artefacts will be filtered out in the downconversion)

>
> DVD Recoders record at a resolution of 720 x 576

For their lower compression modes yes, at the 3hour+ level most drop to
352x576 I believe

>
> This is exactly the same resolution as SDTV broadcasts.

Yep - though some DVB-T broadcasts in the UK are at 544x576.

>
> So in theory the recording will be an exact match of the broadcast.

Final resolution isn't everything in image quality - you have to consider
earlier points in the chain, such as downconversion, compression, the
resolution at which compression is applied etc.

>
> If you record from HD transmassion it will only be recorded at the the DVD
> Recorders max resolution anyway.

Yes - but the quality of the signal being recorded may not be the same.

I'm not saying either the HD downconversion or the direct SD broadcast will
be better - just that it isn't safe to assume they will be identical.

Steve