Are all digital tuners slow?

I recently had my first experience with digital tv by buying an inexpensive
RCA CRT television 20F514TD that had an ATSC/QAM tuner. One thing noticed
was how slow the channels were to display after changing a channel. There
was a 4-5 second delay between changing a channel and the channel actually
being displayed. This was all on cable, not OTA. A friend mentioned that
the delay sure killed the channel surfing experience.

My question is, is the delay in changing channels present in all digital
tuners or do more expensive televisions have better tuners with a shorter
delay?

I eventually returned the RCA to Walmart as there were other problems with
how the picture displayed. While analog channels looked ok, the digital
channels had odd color issues, mostly with tint. The fleshtones took on a
very greenish color on certain scenes. Adjusting the tint control didn't
really correct anything. It's almost like if there was a lot of green in
the picture, everything would be green, including people's hair and skin
color. While the analog side looked ok, the digital channels were overall
very dark. Turning up the brightness and contrast improved things
somewhat, but there still seemed like a great loss of detail in darker
areas of the screen. Messed with it for a few days, but the more I saw the
less I liked. Packed it all back in the box very well, took it back to the
store, just told them I didn't like the tv. That was it, received a
complete refund.

"Cathode Ray" wrote in message
er.mixmin.net...
I recently had my first experience with digital tv by buying an inexpensive
RCA CRT television 20F514TD that had an ATSC/QAM tuner. One thing noticed
was how slow the channels were to display after changing a channel. There
was a 4-5 second delay between changing a channel and the channel actually
being displayed. This was all on cable, not OTA. A friend mentioned that
the delay sure killed the channel surfing experience.

My question is, is the delay in changing channels present in all digital
tuners or do more expensive televisions have better tuners with a shorter
delay?

I eventually returned the RCA to Walmart as there were other problems with
how the picture displayed. While analog channels looked ok, the digital
channels had odd color issues, mostly with tint. The fleshtones took on a
very greenish color on certain scenes. Adjusting the tint control didn't
really correct anything. It's almost like if there was a lot of green in
the picture, everything would be green, including people's hair and skin
color. While the analog side looked ok, the digital channels were overall
very dark. Turning up the brightness and contrast improved things
somewhat, but there still seemed like a great loss of detail in darker
areas of the screen. Messed with it for a few days, but the more I saw
the
less I liked. Packed it all back in the box very well, took it back to
the
store, just told them I didn't like the tv. That was it, received a
complete refund.

There is a difference among TV brands (with respect to tuner delay) even
among analog TV's. One thing that makes it take longer to tune in is if you
have your cable box set to display the native mode (which takes longer to
recognize for each channel) instead of always upscaling to the a fixed
resolution of your TV set (usually the maximum resolution that your TV will
display).

On Sep 2, 1:55 am, Cathode Ray wrote:
I recently had my first experience with digital tv by buying an inexpensive
RCA CRT television 20F514TD that had an ATSC/QAM tuner. One thing noticed
was how slow the channels were to display after changing a channel. There
was a 4-5 second delay between changing a channel and the channel actually
being displayed. This was all on cable, not OTA. A friend mentioned that
the delay sure killed the channel surfing experience.

My question is, is the delay in changing channels present in all digital
tuners or do more expensive televisions have better tuners with a shorter
delay?

I eventually returned the RCA to Walmart as there were other problems with
how the picture displayed. While analog channels looked ok, the digital
channels had odd color issues, mostly with tint. The fleshtones took on a
very greenish color on certain scenes. Adjusting the tint control didn't
really correct anything. It's almost like if there was a lot of green in
the picture, everything would be green, including people's hair and skin
color. While the analog side looked ok, the digital channels were overall
very dark. Turning up the brightness and contrast improved things
somewhat, but there still seemed like a great loss of detail in darker
areas of the screen. Messed with it for a few days, but the more I saw the
less I liked. Packed it all back in the box very well, took it back to the
store, just told them I didn't like the tv. That was it, received a
complete refund.

There's something of a buffer, at least with mine. I enter five steps
at the remote, not bothering to watch for visual confirmation, and
it'll do its thing and eventually get to fifth.

On Sun, 02 Sep 2007 05:55:45 +0000, Cathode Ray wrote:

My question is, is the delay in changing channels present in all digital
tuners or do more expensive televisions have better tuners with a shorter
delay?

It's in all digital tuners. They wait for a signal lock and then process.
Many things can affect this delay time, but it's mostly the signal you
actually get. The actual TV sets shouldn't have much difference in time
connected to the same antenna. They all have to lock and process the
signal before displaying.

--
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"Wes Newell" wrote in message
news:[email protected]
On Sun, 02 Sep 2007 05:55:45 +0000, Cathode Ray wrote:

My question is, is the delay in changing channels present
in all digital
tuners or do more expensive televisions have better
tuners with a shorter
delay?

It's in all digital tuners. They wait for a signal lock
and then process.
Many things can affect this delay time, but it's mostly
the signal you
actually get. The actual TV sets shouldn't have much
difference in time
connected to the same antenna. They all have to lock and
process the
signal before displaying.

--
Want the ultimate in free OTA SD/HDTV Recorder?
http://mythtv.org
http://mysettopbox.tv/knoppmyth.html Usenet
alt.video.ptv.mythtv
My server http://wesnewell.no-ip.com/cpu.php
HD Tivo S3 compared
http://wesnewell.no-ip.com/mythtivo.htm

One other point, once the tuner acquires lock on the signal
for demodulation, it has to wait for an "I" frame in the
MPEG stream before it can display a picture. Long GOP
sequences can add noticeable delay.

David

On Sun, 2 Sep 2007 02:48:25 -0400 Mark A wrote:

| There is a difference among TV brands (with respect to tuner delay) even
| among analog TV's. One thing that makes it take longer to tune in is if you
| have your cable box set to display the native mode (which takes longer to
| recognize for each channel) instead of always upscaling to the a fixed
| resolution of your TV set (usually the maximum resolution that your TV will
| display).

The actual frequency change can lock up in just milliseconds. Syncronizing
to the bit stream could take a little longer, but still just a fraction of
the time of one frame. Recognizing the actual video could could well take
a whole frame of time. That might account for 50ms to 80ms of time. The
rest is some combination of poor software programming and cheap slow CPUs
to run that software.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

On Sun, 02 Sep 2007 15:19:06 GMT Wes Newell wrote:

| It's in all digital tuners. They wait for a signal lock and then process.

If that's so, then there is some bad circuitry. Frequency tuning can go
to the channel in a couple milliseconds. Syncronizing to the bit stream
can take a little longer, but the blocks are clearly a small portion of
the frame time, given that you can see fraction of a picture loss in
signal on marginal reception. Even the resolution mode/format can be
detected at the next frame.


| Many things can affect this delay time, but it's mostly the signal you
| actually get. The actual TV sets shouldn't have much difference in time
| connected to the same antenna. They all have to lock and process the
| signal before displaying.

It depends on what processing is going on. If there is no format scaling
(which adds latency to the signal), it should begin outputting the picture
very quickly.

My brother has a Comcast STB on his analog TV. It exhibits the same
horrible channel change delays even for analog programs output as analog.
It's bad software development, usually in the Java language. Java makes
programming "safe" so employers can hire cheaper less skilled programmers.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

On Sun, 02 Sep 2007 16:13:49 GMT David wrote:
|
| "Wes Newell" wrote in message
| news:[email protected]
| On Sun, 02 Sep 2007 05:55:45 +0000, Cathode Ray wrote:
|
| My question is, is the delay in changing channels present
| in all digital
| tuners or do more expensive televisions have better
| tuners with a shorter
| delay?
|
| It's in all digital tuners. They wait for a signal lock
| and then process.
| Many things can affect this delay time, but it's mostly
| the signal you
| actually get. The actual TV sets shouldn't have much
| difference in time
| connected to the same antenna. They all have to lock and
| process the
| signal before displaying.
|
| --
| Want the ultimate in free OTA SD/HDTV Recorder?
| http://mythtv.org
| http://mysettopbox.tv/knoppmyth.html Usenet
| alt.video.ptv.mythtv
| My server http://wesnewell.no-ip.com/cpu.php
| HD Tivo S3 compared
| http://wesnewell.no-ip.com/mythtivo.htm
|
| One other point, once the tuner acquires lock on the signal
| for demodulation, it has to wait for an "I" frame in the
| MPEG stream before it can display a picture. Long GOP
| sequences can add noticeable delay.

This does not account for 2-3 seconds of delay I see with the Comcast box.
The big reason it does not account for it that the delay exists even for
analog signals output as analog where "GoP" and "I/B-frames" are not part
of what is going on.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|

On Sun, 02 Sep 2007 05:55:45 -0000, Cathode Ray
wrote:

I recently had my first experience with digital tv by buying an inexpensive
RCA CRT television 20F514TD that had an ATSC/QAM tuner. One thing noticed
was how slow the channels were to display after changing a channel. There
was a 4-5 second delay between changing a channel and the channel actually
being displayed. This was all on cable, not OTA. A friend mentioned that
the delay sure killed the channel surfing experience.

My question is, is the delay in changing channels present in all digital
tuners or do more expensive televisions have better tuners with a shorter
delay?

I eventually returned the RCA to Walmart as there were other problems with
how the picture displayed. While analog channels looked ok, the digital
channels had odd color issues, mostly with tint. The fleshtones took on a
very greenish color on certain scenes. Adjusting the tint control didn't
really correct anything. It's almost like if there was a lot of green in
the picture, everything would be green, including people's hair and skin
color. While the analog side looked ok, the digital channels were overall
very dark. Turning up the brightness and contrast improved things
somewhat, but there still seemed like a great loss of detail in darker
areas of the screen. Messed with it for a few days, but the more I saw the
less I liked. Packed it all back in the box very well, took it back to the
store, just told them I didn't like the tv. That was it, received a
complete refund.

Definitely depends on make/model of TV. In fact, if you read a few
reviews, the reviewer is annoyed just like you are and reports on the
speed.

On Sun, 2 Sep 2007 15:59:15 -0700 Bill's News wrote:

| I don't know about Comcast, but recent Adelphia/TW "boxes" only
| monitor the digital stream. If you've an analog device attached
| to their "box" it converts D2A.
|
| The analog stream is, of course, available to analog tuners
| which do not have a "box" between them and the cable.
|
| Of course if your box is quite old, then it may indeed be an
| analog only box.

It has to be a dual digital/analog box because it gets the local access
channels which are not yet on digital, and it gets channels that are on
digital only.

Their next generation boxes might well be digital only. They have said
new boxes are coming soon. If so, they will need to get the content of
the remaining analog only channels onto digital.

--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
| first name lower case at ipal.net / |
|------------------------------------/-------------------------------------|