Ready for Another Subchannel for TMJ4-HD?

[beeper]

For anyone interested on the real-life effect of adding yet another subchannel, here are some reduced-sized screen captures from tonights programming:

Although I've resized these images, the pixelation shown is representative of the original broadcast, they're not resizing artifacts.

Sports programming will look worse.

Scott

How old is your tuner and how are you capturing a frame? Also how do you determine where observed pixelation is introduced? Many times pixelation is introduced before local broadcasting.

If that's what the picture looks like on your end, I can understand why you would habitually complain. My subchannels look better than what you posted. Because of various factors, it would be unfair to assume that others see the same PQ as you do.

I have a 5 year old Samsung LCD 720p HDTV 60Hz 16ms response time and everything looks worse on that. I see motion blur, macroblocking and SD quality is horrible.

On my 2009 1080p LCD HDTV with a newer generation tuner, much higher refresh rate, lower response time and 14 bit processor, the PQ is outstanding compared to the older unit (both HD & especially SD).
Freezing a static frame (like that of the singer you posted) looks like viewing a photo on my PC.
I don't see any of the blocking represented in that frame. Granted, because of your location you probably have a higher bit rate error that your tuner has to deal with.

I see differences in PQ among the local channels, but that normally would be comparing apples to oranges because the differences are mainly in the production, not the local broadcasting.  For example, Ch 58's NFL football production has been poor compared to the other networks. I wouldn't blame the local broadcaster or the number of subchannels for that.

I watched and DVR recorded Americas Got Talent this week and I freeze the picture and I don't see pixelation. There was one segment with someone tumbling where there was macroblocking, but I believe that was on the source.

I also used the MJ memorial to compare differences between channels. This was a fairer apples to apples comparison. 4 and 58 had the best PQ in clarity, brightness, accurate color and tint.
I could clearly see the button holes in Berry gordy's suit on 4 & 58. On 6 & 12 the button holes were not as distinct.

I did not notice pixelation on any channel when freezing the picture.

Channel 12 without any subchannels, decidedly had the poorest quality picture.
Granted these comparisons were mostly static scenes.

6 initially had a dark picture and overly saturated color, so Berry Gordy's suit was barely visible against the black background. The brightness was corrected by Stevie Wonder's song.

12 had the brightness to high so the shots of the audience looked like a hazy smoke filled room. The raised black levels hurt the PQ, which was generally softer in clarity. 12 also had stutter problems several times that changed the broadcast timing compared to the other stations.

58 & 12 had the best quality sound. Both louder because they were not using dialnorm offset of minus 4 like 4 & 6. The separation also seemed better on 58 compared to any other channel.

[beeper]

This is what a captured frame looks like with my limited equipment. This is not a photo, so it will not look as clear as a photo or real time frames viewed on the TV.

This was captured today with a 5 year old tuner that my DVR uses. Two subchannels active.
I can only capture a down converted frame that is compressed and I made it the same resolution as the recent Got Talent frames that were posted. It is also 1/3 of the original file size after uploading to the forum.

Even though it is standard definition, it is still representative of the amount of noise or pixel blocking, compared to your captures.

The actual picture freeze on my 720p or 1080p HDTV is obviously much clearer because of the higher resolution. Neither method of viewing a frame on my end, has the horrendous noise or degree of pixel blocking that your equipment captures.

[SRW1000]

This is what a captured frame looks like with my limited equipment. This is not a photo, so it will not look as clear as a photo or real time frames viewed on the TV.

This was captured today with a 5 year old tuner that my DVR uses. Two subchannels active.
I can only capture a down converted frame that is compressed and I made it the same resolution as the recent Got Talent frames that were posted. It is also 1/3 of the original file size after uploading to the forum.

Even though it is standard definition, it is still representative of the amount of noise or pixel blocking, compared to your captures.

The actual picture freeze on my 720p or 1080p HDTV is obviously much clearer because of the higher resolution. Neither method of viewing a frame on my end, has the horrendous noise or degree of pixel blocking that your equipment captures.

The picture you've posted is of the talking-head type, with very little movement, and is not hard to transmit clearly, even with limited bandwidth.  I'd be shocked to see readily-apparent defects under those conditions, unless there was a cutaway shot to another scene.

The pictures I posted earlier in this thread were captured with an HDHomerun networked tuner.  The reason for the heavy pixelation is due to the highly changing content.  Pans, zooms, and fast motion are a much greater challenge to encoders than are shots consisting of low or limited motion.

I did not have to carefully search, frame by frame, to see the artifacting.  It was readily apparent at normal playback speed.  Because it was so noticeable, I recorded a couple of brief segments and then took frame captures from the troublesome scenes.  The pictures are representative of what I was watching in real time on my other HD tuners.

Some people are not bothered at all by such defects, and do not notice them as easily as other people do.

Next time you're watching a sports event on either of the network stations that multicast, pay attention during a panning shot.  That's when the pixelation is most easily scene.  You shouldn't even have to pause the picture to see it, but pausing it will confirm the problem.

If you primary viewing is Meet the Press, local news, and courtroom dramas this isn't going to be a big issue for you.

Scott

[NET10]

Can someone give me a Dummies Guide To Re-scanning on a HR20-100?  I can't figure out how to receive 4-3 and 6-2.
Thanks

[beeper]

The picture you've posted is of the talking-head type, with very little movement, and is not hard to transmit clearly, even with limited bandwidth.  I'd be shocked to see readily-apparent defects under those conditions, unless there was a cutaway shot to another scene.

Scott

That's why I was shocked that the fairly static Got Talent frame that you posted of a "talking head type" was such poor quality. I watched that segment and there was very little movement during those shots, and no apparent degradation of the PQ on my end.

It looks like your tuner was on the verge of loosing the signal.

Strangely, the second frame that you posted that was a movement frame (and would be blurred on the source) has much less obvious pixelation and noise vs. the static frame.

So how old is the tuner, and what type of display are you using?

[MDR]

Can someone give me a Dummies Guide To Re-scanning on a HR20-100?  I can't figure out how to receive 4-3 and 6-2.
Thanks

I think it's dependent upon DTV's database. I have a AM-21 with a HR-21 and did a reset and those channels don't show up in their channel list. To be sure try contacting DTV and tell them those channels are missing.
MDR

[SRW1000]

That's why I was shocked that the fairly static Got Talent frame that you posted of a "talking head type" was such poor quality. I watched that segment and there was very little movement during those shots, and no apparent degradation of the PQ on my end.

It looks like your tuner was on the verge of loosing the signal.

Strangely, the second frame that you posted that was a movement frame (and would be blurred on the source) has much less obvious pixelation and noise vs. the static frame.

So how old is the tuner, and what type of display are you using?

The static picture I posted was from a transition from one scene to another.  It's not the tuner losing it's signal.  I posted what I used to capture the frame in the above post.

Scott

[SRW1000]

I mentioned sports earlier.  Here's a screen shot from today's programming:

This has been resized, and the compression artifacts are noticeable.

Looking at it full-sized, they're obnoxious.  Here's a crop of the picture, full sized:



This has not been resized, just a simple crop, so the compression artifacts are not a result of image manipulations.

Jamming one HD and two SD stations does not allow enough bandwidth for quality HD programming.

Scott

[beeper]

I mentioned sports earlier.  Here's a screen shot from today's programming:

Jamming one HD and two SD stations does not allow enough bandwidth for quality HD programming.

Scott

Now we're getting somewhere.

The recorded broadcast of the swimming does admittedly have macro blocking in various places on the source. It's already on the source before the signal hits the local satellite dish.

What you are seeing in that recording is the same as going into Best Buy and watching the in store recording and seeing macro blocking on every TV at the same time in the recording, every time it is viewed.

You are killing the messenger by blaming local channels for a poor recording.

Did you notice that during the swimming broadcast, when commercials were run, there wasn't any hint of macro blocking. (during movement, fast pans and frame transitions.) Then when returning to the swimming, there was some noticeable macro blocking. What does that tell you? Is channel 4 increasing the bit rate during commercials? Of course not. It tells you that the macro blocking is on the recording. Sub channels or not, that recording would have macro blocking, when broadcast.

When the programming changed to the live golf, the quality improved significantly. When the camera would pan fast upwards following the ball, there was nothing like seen on the swimming recording.

If you did see the short recordings of some baseball, golf and pro football talk at the beginning of the golf, you most likely would have regurgitated during the football clip. It was atrocious.  Again, no fault of the local broadcaster. It is what they were dealt. The baseball and golf clips did not have massive macro blocking like the football clip.

Your captured frames do have a striking pixel block pattern that is widespread. As you may know, the quality of what you see with your particular tuner is at the mercy of whatever you are using for decoding. Have you tried any other HD tuners with an HD monitor to verify what you are now seeing is duplicated on other equipment?

Are you using Ethernet or WiFi to your decoder? WiFi can have problems with that particular tuner if you have not done your homework.

Here are some frames of the swimming recording. Again the file sizes have been greatly reduced after uploading and I can only capture a down converted signal.
The dive frames have some reflections of the (brick like) bottom of the pool.

[SRW1000]

Now we're getting somewhere.

The recorded broadcast of the swimming does admittedly have macro blocking in various places on the source. It's already on the source before the signal hits the local satellite dish.

What you are seeing in that recording is the same as going into Best Buy and watching the in store recording and seeing macro blocking on every TV at the same time in the recording, every time it is viewed.

You are killing the messenger by blaming local channels for a poor recording.

Granted, network programing can have it's own issues, but what makes you think that reducing available bandwidth would not have an even stronger negative effect on picture quality?  Do you have access to the network source material?  If so, it would make a great comparison.

Did you notice that during the swimming broadcast, when commercials were run, there wasn't any hint of macro blocking. (during movement, fast pans and frame transitions.) Then when returning to the swimming, there was some noticeable macro blocking. What does that tell you? Is channel 4 increasing the bit rate during commercials? Of course not. It tells you that the macro blocking is on the recording. Sub channels or not, that recording would have macro blocking, when broadcast.

Below are some captures of the commercials that were played during the swimming program.  The first two were from a Universal Sports commercial, the third was from an NBC golf promo.  Let me know if you see any macroblocking:


Image size reduced.


Image cropped, but not resized.


Image size reduced.


Image cropped, but not resized.


Image size reduced.


Image cropped, but not resized.

When the programming changed to the live golf, the quality improved significantly. When the camera would pan fast upwards following the ball, there was nothing like seen on the swimming recording.

If you did see the short recordings of some baseball, golf and pro football talk at the beginning of the golf, you most likely would have regurgitated during the football clip. It was atrocious.  Again, no fault of the local broadcaster. It is what they were dealt. The baseball and golf clips did not have massive macro blocking like the football clip.

Sorry, missed that programming, so I can't comment.

Your captured frames do have a striking pixel block pattern that is widespread. As you may know, the quality of what you see with your particular tuner is at the mercy of whatever you are using for decoding. Have you tried any other HD tuners with an HD monitor to verify what you are now seeing is duplicated on other equipment?

Are you using Ethernet or WiFi to your decoder? WiFi can have problems with that particular tuner if you have not done your homework.

The tuner is hardwired, not WiFi.  As I stated earlier, the images I've captured mirror what is easily visible on any of my tuners.

If I have the chance to capture some NBC programming from Green Bay and post comparisons.  I don't believe they're multicasting at this time.

Scott

[beeper]

Below are some captures of the commercials that were played during the swimming program.  The first two were from a Universal Sports commercial, the third was from an NBC golf promo.  Let me know if you see any macroblocking:

If I have the chance to capture some NBC programming from Green Bay and post comparisons.  I don't believe they're multicasting at this time.

Scott

Correct, channel 26 in GB is not multicasting. That would be an apples to oranges comparison anyway unless both stations have exactly the same equipment.

I do not see macro blocking in your frames from commercials. Whatever it is though, is ugly and I don't think everyone else is seeing what you're seeing. It is like looking through faceted glass. Macro blocking would not cover every square inch of the frame like the pattern in your captured frames.

I'm beginning to think that any frame you capture would have that pattern introduced from something unknown. What does a frame from 12, 18 or 24 look like?

Do you have an antenna preamp or distribution amp? If so, have you tried bypassing it?

[tencom]

Why do people only believe that data reduction compression only occurs in the temporal mode, also called the inter mode, which is motion compression, which can cause macroblocking if aggressively applied. There is another compression mode used that is called spatial compression, also called intra- compression which occurs with-in the picture and  appears to be the data reduction technique used on existing video streams and added streams,  by broadcasters, when adding more video streams  to their existing  channels. This is a technique that throws out picture detail taking in account the human visual system and hoping the loss of detail  will not be noticed by the viewer but to me is quite noticable.The only way you can confirm this is by comparing the compressed video with the original source video but probably will be quite apparent to any viewer. That is why HD video could be called SEMI-HDTV since it may not ultilize the complete bandwidth that true HD is capable of.

[SRW1000]

Correct, channel 26 in GB is not multicasting. That would be an apples to oranges comparison anyway unless both stations have exactly the same equipment.

Since I have no access to the direct feed, comparing the same frames from 4.1 to 26.1 would be the closest test possible.

I do not see macro blocking in your frames from commercials. Whatever it is though, is ugly and I don't think everyone else is seeing what you're seeing. It is like looking through faceted glass. Macro blocking would not cover every square inch of the frame like the pattern in your captured frames.

I'm beginning to think that any frame you capture would have that pattern introduced from something unknown.

What you're seeing is the encoder struggling with complex material, and reducing it to fit within the allocated bandwidth.

What does a frame from 12, 18 or 24 look like?

These kinds of patterns are evident on every source.  Here's a capture from 12.1:


Image size reduced.

This is one of the worst torture tests you can find.  The moving water is a challenge for any encoder.  You can see some pixelation in the red portion of the frame.

What's the difference between this picture and the 4.1 picture?  Well, the compression in this sceene was not readily apparent at full speed.  I had to actually look at frames to pick one out.  In contrast, I chose the 4.1 frames based on what I observed while simply watching the show.  Secondly, look at how even a slow pan causes problems with 4.1 in the golf scene above.  That's not demanding material.

Do you have an antenna preamp or distribution amp? If so, have you tried bypassing it?

These problems are not the result of amplificaton.

Scott

[SRW1000]

Why do people only believe that data reduction compression only occurs in the temporal mode, also called the inter mode, which is motion compression, which can cause macroblocking if aggressively applied. There is another compression mode used that is called spatial compression, also called intra- compression which occurs with-in the picture and  appears to be the data reduction technique used on existing video streams and added streams,  by broadcasters, when adding more video streams  to their existing  channels. This is a technique that throws out picture detail taking in account the human visual system and hoping the loss of detail  will not be noticed by the viewer but to me is quite noticable.The only way you can confirm this is by comparing the compressed video with the original source video but probably will be quite apparent to any viewer. That is why HD video could be called SEMI-HDTV since it may not ultilize the complete bandwidth that true HD is capable of.

This is an excellent point.

The reason I'm focusing on the pixelation is that it's very easy to spot, based on it's unnatural appearance.

As you mentioned, spatial compression is also a problem, but without access to the source material, it's difficult to confirm.  Looking at some of the frames from the swimming scenes, it does look like detail has been softened, but that could be attributed to the way it was filmed.

Again, if I can get some frames from 26.1, I'll try and post a direct comparison, which may show additional loss of detail.

Scott

[beeper]

Since I have no access to the direct feed, comparing the same frames from 4.1 to 26.1 would be the closest test possible.

Scott

Even though it would be different broadcasting equipment and settings, a comparison of identical frames from 26.1 and 4.1 would be interesting.

Well, the compression in this sceene was not readily apparent at full speed.

Monitor type, size and era would affect the quality that a viewer would see "full speed". My largest 16:9 monitor is 42".

You neglected to answer my previous question regarding the monitor you are using. What's  the brand/model or specs of the best monitor that you are using?