The state of Broadcast and Provider delivered HD - Page 3 - AVS Forum
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post #61 of 83 Old 10-11-2012, 09:36 AM
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Originally Posted by NetworkTV View Post

Right...but...
It's possible to have lossy compression that is still invisible.
We all know that JPEG compression in photos is lossy, but with the right content and theright settings for that content, most people would be unlikely to spot a difference between the recompressed photo and the RAW image - especially considering they would likely be viewing it on a screen or printout that is capable of significantly less than the full resolution of the image.
Most modern, low dynamic range pop music would sound identical in 192mb/s MP3 as it would on a CD or even higher quality media. It's all averaged out to have no more than 6-8db of dynamic range anyway. On the other hand, well recorded and master classical music can easily benefit from the highest possible quality medium due to the vastly higher dynamic range and frequencies at play.
That's why you can't rely any one factor in judging quality.
If you can't tell the difference, it doesn't matter if recompression takes place. What matters is how it looks.

Correct, but you have to monitor your MPEG stream before and after you Transcode to look for PID errors, sure it is labled a compression but some people automatically percieve this a down grade in quality which it is not.

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post #62 of 83 Old 10-11-2012, 12:51 PM
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Originally Posted by mrvideo View Post

Again, reducing the bits by using H.264 won't help, because the a-hole suits will just cram more stuff into the mux.

Here's why I don't want H.264.

When you decrease the bandwidth for MPEG-2, it falls apart pretty badly. You get blocking, mosquito noise, and lots of ugliness. That's the nature of the codec.

H.264 on the other hand is very graceful when bandwidth is decreased. You might see some funny blocky backgrounds or banding in subtle color gradients but it generally produces softer and softer images as there are fewer bits available. Most motion is well reproduced with minimal bandwidth -- you don't see 16x16 pixel blocks jumping off the screen like with MPEG-2.

And that's what will happen. They'll decrease the bandwidth more and more. The picture won't crumble unacceptably like it would with MPEG-2. It will just get softer and softer until we're getting DVD quality video. Most people won't notice or care since it will still look good for what it is.

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post #63 of 83 Old 10-11-2012, 01:25 PM
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Originally Posted by scowl View Post

Here's why I don't want H.264.
When you decrease the bandwidth for MPEG-2, it falls apart pretty badly. You get blocking, mosquito noise, and lots of ugliness. That's the nature of the codec.
H.264 on the other hand is very graceful when bandwidth is decreased. You might see some funny blocky backgrounds or banding in subtle color gradients but it generally produces softer and softer images as there are fewer bits available. Most motion is well reproduced with minimal bandwidth -- you don't see 16x16 pixel blocks jumping off the screen like with MPEG-2.
And that's what will happen. They'll decrease the bandwidth more and more. The picture won't crumble unacceptably like it would with MPEG-2. It will just get softer and softer until we're getting DVD quality video. Most people won't notice or care since it will still look good for what it is.

The problem is, right now, what your asking for is a guaranteed bad picture with things the way they are on the chance that they'll want to cram more stuff into the stream later.

The fact is, they're going to do what they're doing now and that isn't going to change for the better. As a result, I'd rather let them have the room and potentially end up with some softness later than see the image go completely blocking every time police cars, dance clubs or shaky cam footage is on the screen the way it does now.


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post #64 of 83 Old 10-11-2012, 03:43 PM
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Originally Posted by NetworkTV View Post

The problem is, right now, what your asking for is a guaranteed bad picture with things the way they are on the chance that they'll want to cram more stuff into the stream later.
The fact is, they're going to do what they're doing now and that isn't going to change for the better. As a result, I'd rather let them have the room and potentially end up with some softness later than see the image go completely blocking every time police cars, dance clubs or shaky cam footage is on the screen the way it does now.

Since I control the bandwidth my system I don't have any problems. When more companies get on board with FTTH and realize that they are beating a dead horse with old coax plant the better.

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post #65 of 83 Old 10-11-2012, 04:43 PM
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i posted on the dish thread about a month ago that i was perceiving noticeably deteriorating pq. didn't get much of a response.

but my take on this seems to be confirmed with the posts on this thread.

while i believe my local comcast probably sends out a slightly higher quality transmission, i don't think it that much better to justify
another $50-60 a month for the same service (2 hd dvrs in the house plus hbo and movie package) l love dish's affordable programming but
not the quality of their hd.\

only on a good b.r. transfer can i really enjoy hd kickass pq.

just rented battleship and while the plot is inane, man that was fun to watch.

neflixis our nemesis
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post #66 of 83 Old 10-12-2012, 02:23 AM
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Originally Posted by ybsane View Post

Quality of your feed is important also, DVB-S QPSK can look OK while DVB-S2 8psk looks stellar.

I don't know, but I've seen many stellar DVB-S QPSK feeds. It is hard to tell MPEG-2 @ 35-40 Mbps from DVB-S2 H.264 @ 20 Mbps.

With GDMX feeds, you are lucky to get 15 Mbps H.264.

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post #67 of 83 Old 10-12-2012, 10:47 AM
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Originally Posted by mrvideo View Post

I don't know, but I've seen many stellar DVB-S QPSK feeds. It is hard to tell MPEG-2 @ 35-40 Mbps from DVB-S2 H.264 @ 20 Mbps.
With GDMX feeds, you are lucky to get 15 Mbps H.264.

From my point of view I have seen better overall picture quality with all of my feeds going to DVB-S2 H.264, the FEC on the DVB-S feeds is usally around 3/4 and the S2's are anywhere from 5/6 to 9/10 which in my book is more content and less correction. Of course we are all allowed to have our opinions,which keeps this forum interesting...smile.gif

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post #68 of 83 Old 10-12-2012, 11:23 AM
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Ok. For my continuing education, what exactly is DVB-S QPSK, DVB-S2, and FEC and how do they compare to OTA (8VSB)? I basically understand what they are but I'd like a little more in-depth explanation.
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post #69 of 83 Old 10-12-2012, 07:25 PM
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Originally Posted by Otto Pylot View Post

Ok. For my continuing education, what exactly is DVB-S QPSK, DVB-S2, and FEC and how do they compare to OTA (8VSB)? I basically understand what they are but I'd like a little more in-depth explanation.

DVB = Digital Video Broadcast
DVB-T = Terrestrial (UK and Europe OTA for example)
CVB-T2 - Terrestrial version 2
DVB-S - Satellite
DVB-S2 - Satellite version 2

QPSK - Quad Phase Shift Keying
8PSK - 8 Phase Shift Keying

http://en.wikipedia.org/wiki/Phase-shift_keying

FEC - Forward Error Correction. The first part of the number is # of data bit in the bit count (2nd number). So, 3/4 means 3 data bits and 1 error correction bit. 9/10 means 9 data bits and 1 correction bit.

ATSC is very much like DVB as to how the transport stream is assembled.

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post #70 of 83 Old 10-12-2012, 07:29 PM
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Originally Posted by ybsane View Post

From my point of view I have seen better overall picture quality with all of my feeds going to DVB-S2 H.264, the FEC on the DVB-S feeds is usally around 3/4 and the S2's are anywhere from 5/6 to 9/10 which in my book is more content and less correction.

I do not disagree that doing DVB-S2 with H.264 is a preferred method. Just that with 30-40 Mbps MPEG-2, it is hard to go wrong, compared to OTA doing 15 Mbps MPEG-2.

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post #71 of 83 Old 10-13-2012, 08:32 AM
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Bit late to the party but ...

I think with video transcoding the video is decoded to DCT and then re-encoded, so it doesn't need to go fully to baseband. I don't know if the motion vector information from the source is re-used in any way. Of course this assumes going from one DCT based compression scheme to another. DWT (like JPEG2k) is another matter.

As for those fond memories of CRT based displays, I'm glad we're finally past them. They did have some advantages such as the inherit exponential gamma with good dark area performance. The down sides included most consumer sets didn't have good phosphor colorimetry. It's common now that displays have wider gamut than the 709/601 specifications. Those RCA CRTs had poor enough scanning linearity that one could see the image stretch and compress on pans. Blooming and mis-registration were common issues on consumer sets, and even getting that near perfect on professional ones was a challenge. Lifetime on CRTs seemed to decrease once HD started, and on the professional monitors (such as the 32" Sony) was around three years with the replacement being very costly. CRTs also had lag, though not nearly as bad as some LCDs that were released. Phosphor burn was an issue, though not as bad as plasma. My own opinion is that I've never really liked plasma and I'm happy to see it fading away.

The newer technologies can have many advantages over CRTs. One mentioned earlier is expanded gamut. Even if this expanded area (deeper colors) isn't utilized, it still provides a greater area to use a matrix or LUT to create exacting chomaticity coordinates. Since most displays require exponential gamma correction, this can be used to create accurate gamma (assuming enough bits are used to avoid quantizing errors). Mis-registration is a thing of the past on direct view and sequenced color displays. Consumer 4K is now around the corner. Lag on the newer LCDs is minimal, and newer technologies such as OLED even better.

The ultimate to me is the display Sony demonstrated at CES this year with LEDs. If it had flaws, I didn't see them. Great color, no lag at all, fantastic blacks. Of course this isn't ready even for professional markets yet, but it does show that the best is yet to come. OLEDs look to offer improved images for now.

I will agree that both broadcast and most of the providers have compromised quality for quantity. However, there have been improvements. DirecTv was widely criticized on this site for its poor HD quality, but they improved when they went to MPEG4. NBC also improved very noticeably when they switched to MPEG4 network distribution not only for the image but on the audio too. The 5.1 audio is all in time now (no echos or hollow sound) and in lip sync. Live cameras are better than the early days. 4K film scanning allows better transfers. I don't know if the move to electronic acquisition for episodics and features has necessarily been a good thing, but to be sure film is fading.

We're still in a state of transition from SD and MPEG2. This wastes providers bandwidth. It will probably be quite some time before OTA goes with an improved codec, but providers can take better advantage of these advances. I still think the providers should source their station feeds directly from the broadcaster in baseband with better than OTA encoding, and then advertise "better than antenna quality". Internet streaming will be better to take advantage of improved codecs, though it could be argued that it will just allow the same (or poorer) quality to be sent at lower bitrates. With both bandwidth and codecs improving, there may be reason for optimism. At least on VOD material. The recent server overloads on the O'Reilly-Stewart debate demonstrates there's still problems with live streaming.


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post #72 of 83 Old 10-13-2012, 09:51 AM
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Originally Posted by mrvideo View Post

DVB = Digital Video Broadcast
DVB-T = Terrestrial (UK and Europe OTA for example)
CVB-T2 - Terrestrial version 2
DVB-S - Satellite
DVB-S2 - Satellite version 2
QPSK - Quad Phase Shift Keying
8PSK - 8 Phase Shift Keying
http://en.wikipedia.org/wiki/Phase-shift_keying
FEC - Forward Error Correction. The first part of the number is # of data bit in the bit count (2nd number). So, 3/4 means 3 data bits and 1 error correction bit. 9/10 means 9 data bits and 1 correction bit.
ATSC is very much like DVB as to how the transport stream is assembled.

Thanks.
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post #73 of 83 Old 10-13-2012, 11:11 AM
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Originally Posted by mrvideo View Post

I do not disagree that doing DVB-S2 with H.264 is a preferred method. Just that with 30-40 Mbps MPEG-2, it is hard to go wrong, compared to OTA doing 15 Mbps MPEG-2.

If we are going that route how about CBS's MPEG-2 back hauls of high bit rate 4:2:2...smile.gif Now those are exceptional.

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post #74 of 83 Old 10-13-2012, 11:40 AM
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Originally Posted by TVOD View Post

NBC also improved very noticeably when they switched to MPEG4 network distribution not only for the image but on the audio too. The 5.1 audio is all in time now (no echos or hollow sound) and in lip sync.

The improvement is NBC's audio wasn't a direct result of going to H.264. NBC, like ABC, delivers 5.1 audio as three stereo pairs that contain the discrete audio, which is then encoded at the affiliate to DD5.1. When NBC went to H.264, they had to change out the encoders and IRDs at the affiliates,. One of the requirements of the new gear was the zero phase issue with the audio.

So, audio improvement was a side effect, though a requirement,of the new gear. biggrin.gif

A problem with using the stereo MPEG audio streams is that they are 16 bit, not 24 bit that is provided with the CBS and CW Dolby-E audio. GDMX syndicated and Canadian feeds also use 24 bit Dolby-E.

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post #75 of 83 Old 10-13-2012, 11:46 AM
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If we are going that route how about CBS's MPEG-2 back hauls of high bit rate 4:2:2...smile.gif Now those are exceptional.

Actually they are backup front hauls. A back haul would mean that the feed was going from the broadcast center back to the venue. The term has been misused by pretty much everyone for decades, me included.

But, those 70 Mbps 4:2:2 feeds are indeed great. Thing is, they are a backup for the main fiber feed, which is at least twice that bitrate. It is nice that CBS does do a backup at that bitrate for shows like the Grammys, but once the stations get hold of the video and compress the hell out of it, it is nothing but macroblocks during high video activity. What a waste.

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post #76 of 83 Old 10-13-2012, 03:20 PM
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I've got OTA recordings from when they began (in my area) using a MyHD card (I think that is what is was). I've even got copies of the test videos wink.gif I've also got copies from DTV when they were first transmitting in mpeg2. Anyway, I was having this discussion with my son-in-law and I pulled out some of the old recordings comparing then to what is transmitted now and there is no comparison. The old copies smoke the new transmissions. I even played some captures from first season of NCIS (it video showed over 17mb/s) to compare to captures now and you can really see how much worse it is now, esp. since the current OTA transmissions have two additional sub-channels to grab bandwidth. We were watching them on my JVC projector @ 110". I also had one of the first HD boxes (rca dtv dtc-100? that was modded to allow recording via USB) and only thing available on DTV was HBO and one pay per view movie channel. Times have changed as far as quantity but quality definitely sucks.
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post #77 of 83 Old 10-14-2012, 07:02 AM
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Scowl said it best: "They'll decrease the bandwidth more and more. The picture won't crumble unacceptably like it would with MPEG-2. It will just get softer and softer until we're getting DVD quality video. Most people won't notice or care since it will still look good for what it is."

IMHO the various channel people (cable, Sat, streamers) are finding that they can move towards DVD video and sound quality and people are not yelling. Well they have no where to go for the most part. I was comparing the bit rate off of BD Mad Men to what we are seeing on Amazon streaming and HD TV. It is a visible and audible difference and it isn't close. They have figured out that if they broadcast or stream DVD quality at 1080 or 720 they can meet the legal requirements of advertising, rent you a "HD" box, and charge you for HD in adddition to digital etc. This combined with the level of commercials and pop ups and other screen wasters that can't be fast forwarded thru have reduced the "experience" to something which is pretty poor. We are moving to if the series makes it past a season or so and looks interesting we just buy the BD instead. Since we aren't big sports watchers, I can see a point where we drop the TV side of life completely. We know they see what is happening on the internet/browser side; most of the bandwidth is consumed by calls to ad servers and constantly pushing ad updates on pages. People just accept it and that is where we are going on the "broadcast" side. Low/soft resolution in 1080/720 and more ads than content on the screen.
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post #78 of 83 Old 10-14-2012, 08:38 AM
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Originally Posted by TVOD View Post

Bit late to the party but ...
I think with video transcoding the video is decoded to DCT and then re-encoded, so it doesn't need to go fully to baseband. I don't know if the motion vector information from the source is re-used in any way. Of course this assumes going from one DCT based compression scheme to another. DWT (like JPEG2k) is another matter.

All current transcoders on the market go all the way to baseband. It was found pretty early on that this provided the best picture quality.

A Silicon Valley company (Xilient, now called Zenverge after Xilinx threatened a lawsuit) actually tried the DCT only approach. They abandoned the approach and their current line of trancoders do a full decode and encode.

http://ewh.ieee.org/r6/scv/sps/200711Abstract.htm

Also, many transcoders like the Motorola DSR-6100 do additional processing (the DSR-6100 creates the ESPN SD channel from the HD feed), so it has to decode to baseband anyway,

Ron

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post #79 of 83 Old 10-14-2012, 03:30 PM
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Originally Posted by mrvideo View Post

The improvement is NBC's audio wasn't a direct result of going to H.264. NBC, like ABC, delivers 5.1 audio as three stereo pairs that contain the discrete audio, which is then encoded at the affiliate to DD5.1. When NBC went to H.264, they had to change out the encoders and IRDs at the affiliates,. One of the requirements of the new gear was the zero phase issue with the audio.
So, audio improvement was a side effect, though a requirement,of the new gear. biggrin.gif
A problem with using the stereo MPEG audio streams is that they are 16 bit, not 24 bit that is provided with the CBS and CW Dolby-E audio. GDMX syndicated and Canadian feeds also use 24 bit Dolby-E.
While it's true that NBC was using 3 MPEG audio streams before for 5.1 and continue to now, the difference is that the new Tandberg MPEG4 system uses "Phase aligned MPEG-1 Layer II audio ", which allows much better interchannel timing. It's difficult enough just to ensure A/V sync to a few milliseconds, but even that amount causes major problems in interchannel timing. So while it's true that the MPEG4 encoding of the video wasn't a factor, the MPEG4 encoding scheme used by Tandberg (now Ericsson Television) did. I don't think bit depth is relevant for timing.
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A back haul would mean that the feed was going from the broadcast center back to the venue. The term has been misused by pretty much everyone for decades, me included.
News to me and any network (broadcast and cable) and facility I've dealt with. Never heard it called a backup front haul. I've heard the network distribution referred to as a front haul. The feed from the broadcaster to the venue has been referred to as the "return feed". Oh well, guess we all need to change now smile.gif


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post #80 of 83 Old 10-14-2012, 03:46 PM
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Originally Posted by dr1394 View Post

All current transcoders on the market go all the way to baseband. It was found pretty early on that this provided the best picture quality.
A Silicon Valley company (Xilient, now called Zenverge after Xilinx threatened a lawsuit) actually tried the DCT only approach. They abandoned the approach and their current line of trancoders do a full decode and encode.
http://ewh.ieee.org/r6/scv/sps/200711Abstract.htm
Also, many transcoders like the Motorola DSR-6100 do additional processing (the DSR-6100 creates the ESPN SD channel from the HD feed), so it has to decode to baseband anyway,
Ron
Thanks for the info, I wasn't sure. It seemed going through baseband would require extra low pass filtering and DCT re-quantizing which might be undesirable. But, then again, perhaps this would help eliminate some extraneous noise too. The DSR-6100 is a good example of going from MPEG4 to MPEG2. Going from HD, particularly a progressive format @ 60p, to SD interlaced would certainly seem to require a trip through baseband.


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post #81 of 83 Old 10-14-2012, 04:08 PM
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Originally Posted by TVOD View Post

While it's true that NBC was using 3 MPEG audio streams before for 5.1 and continue to now, the difference is that the new Tandberg MPEG4 system uses "Phase aligned MPEG-1 Layer II audio ", which allows much better interchannel timing. It's difficult enough just to ensure A/V sync to a few milliseconds, but even that amount causes major problems in interchannel timing. So while it's true that the MPEG4 encoding of the video wasn't a factor, the MPEG4 encoding scheme used by Tandberg (now Ericsson Television) did. I don't think bit depth is relevant for timing.

They could have continued to use MPEG-2 with the new encoders/IRDs, but obviously they wouldn't have been able to get as many streams as they would have liked. That is why I said that MPEG-4 had nothing to do with the better audio streams.

I mentioned the bit depth only for the dynamic range, and noise floor, of 24 bit vs 16 bit. In theory they could have gone to 24 bit PCM discrete streams. But, nobody out in TV viewer land is going to notice the difference between 16 and 24 bit audio. so why bother. Hell, the macroblocking video is more obvious. biggrin.gif
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News to me and any network (broadcast and cable) and facility I've dealt with. Never heard it called a backup front haul. I've heard the network distribution referred to as a front haul. The feed from the broadcaster to the venue has been referred to as the "return feed". Oh well, guess we all need to change now smile.gif

Yes, they are front hauls. While they don't use the word backup as well, for the major venues, they are indeed backups to the main fiber connection. Obviously if they are out in some location where fiber isn't available, it becomes the only feed biggrin.gif

You're right, "return feed" is a better term. Not sure where backhaul came from, as it was in use before I got into this, a few decades ago.

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post #82 of 83 Old 10-15-2012, 09:39 AM
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They could have continued to use MPEG-2 with the new encoders/IRDs, but obviously they wouldn't have been able to get as many streams as they would have liked. That is why I said that MPEG-4 had nothing to do with the better audio streams.
From the RX1290 brochure: "Phase aligned MPEG-1 Layer II audio capability (MPEG-4 modes only)"


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post #83 of 83 Old 10-15-2012, 05:55 PM
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From the RX1290 brochure: "Phase aligned MPEG-1 Layer II audio capability (MPEG-4 modes only)"

Interesting. Thanks for the update. I wonder why that is.

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