HDMI 1.3 and Cables Part 1: It's All in the Bitrate

[admin]

With the advent of HDMI v1.3 and 1.3a, consumers are starting to really get confused about cables and what they need to worry about when selecting a product that's going to be compatible with the new specifications. We interviewed Steven Barlow from DVIGear to get a handle on why this is a more complex issue for some, and a non-issue for others. He allowed us to assimilate much of what we discussed into this article you are reading now.

Discuss "HDMI 1.3 and Cables Part 1: It's All in the Bitrate" here. Read the article.

 

[Warpdrv]

OOOhhh Im looking forward to reading this.... Thanks for the article, just don't have time right now....

 

[agarwalro]

I had no idea... What an eye opener! Thanks for the article Clint.

 

[stratman]

Very interesting and informative, I wonder how much of the equipment out there touting 1080p and hdmi 1.3 is really capable of delivering.

 

[Audioholics]

Oh just wait until part 2 which goes into the rather unbelievable practices of one of the main companies behind HDMI. It will be absolutely eye-opening.

 

[stratman]

This would fit like a glove to a "Truth and Ethics in Advertising", I guess the government doesn't want to or care to get involved.

 

[AcuDefTechGuy]

Very interesting and informative, I wonder how much of the equipment out there touting 1080p and hdmi 1.3 is really capable of delivering.

You mean like those TVs that say "1080p HDTV", but are actually 1080i and claims to "upconvert" to 1080p? I hate that.

 

[MDS]

You mean like those TVs that say "1080p HDTV", but are actually 1080i and claims to "upconvert" to 1080p? I hate that.

I've seen that type of criticism a lot but the confusion lies in a misunderstanding on the part of consumers.

No HDTV is 1080i. All HDTVs are progressive scan. 1080i may be the highest resolution it can accept as an input but it will always scale whatever is input to its native resolution. So if this tv 'upconverts' to 1080p then it IS 1080p - its native resolution is 1920 x 1080p. It just cannot accept a native 1080p signal as an input.

 

[Highbar]

All this almost makes me glad that I don't have any money to upgrade right now. Hopefully by the time I have money all of this will be worked out. I'm looking forward to an HD format that is problem free when I upgrade.

T

 

[gus6464]

Wait so does this mean that because of the bandwith technically a 1.3 tv and player can offer a better image than a non 1.3 one?

 

[mtrycrafts]

With the advent of HDMI v1.3 and 1.3a, consumers are starting to really get confused about cables and what they need to worry about when selecting a product that's going to be compatible with the new specifications. We interviewed Steven Barlow from DVIGear to get a handle on why this is a more complex issue for some, and a non-issue for others. He allowed us to assimilate much of what we discussed into this article you are reading now.

How does this mesh with the hi def DVDs max transfer rates of 36 or 54Mbits/s?
Isn't this the transfer rate going through the cables? A bit of difference between this and the Gbit rate in the article.

 

[stratman]

Oh just wait until part 2 which goes into the rather unbelievable practices of one of the main companies behind HDMI. It will be absolutely eye-opening.

It wouldn't happen to be anything like this: "Featuring the latest HDMI 1.3a specification, this receiver supports both 1080p/24 and 1080p/60, along with 12-bit Deep Color per channel on compatible TVs."

Said receiver: Denon AVR-3808CI

 

[MDS]

How does this mesh with the hi def DVDs max transfer rates of 36 or 54Mbits/s?
Isn't this the transfer rate going through the cables? A bit of difference between this and the Gbit rate in the article.

A DVD is much lower resolution and the audio is separate. In addition to the higher resolution of HD images, HDMI must carry the audio as well as a lot of 'overhead' - the HDCP crap and various sync bits and meta-data.

 

[mtrycrafts]

A DVD is much lower resolution and the audio is separate. In addition to the higher resolution of HD images, HDMI must carry the audio as well as a lot of 'overhead' - the HDCP crap and various sync bits and meta-data.

http://en.wikipedia.org/wiki/HD_DVD

Go down to the bottom of the page with the chart for bitrates. The numbers I quoted came from it and is the max with video and audio for Hi Def DVDs. So, if that is the max it can download, isn't that the bitrate in the HDMI cable?
Also, the discs carry 30Gb or 50Gb of data, total. If you transfer 1 Gb/s, that is a 50 second shot, disc is over. What am I missing with the numbers here?

 

[MDS]

Those numbers in the Wikipedia chart are the maximums that can be used given all the combinations of mandatory and optional formats. How much space each of the audio and video formats take up on the disc will vary with the compression codec and its settings. I don't know the exact breakdown but so much is allocated for video and so much for audio.

To give an absurd example, say the disc capacity was 10 MB and the audio formats were raw PCM and MP3. In that 10 MB of space I can store (roughly) 1 minute of 2 channel audio in PCM format or three 3 minute MP3 encoded songs at 128 kbps or two 4 minute MP3 encoded songs at 192 kbps. So that is the relationship between the storage available on the disc and the bitrate of the data.

Now we have to actually transfer that data over a wire and that requires some communication protocol which transmits more than just the actual data. The protocol, HDMI in this case, needs far more bits than just the actual data. I can't give a good concrete example because I'm not familiar with the actual data format it uses but just think about all the stuff it does at once - audio, video, control signals, exchanging encryption keys with the sink device, etc.

 

[mtrycrafts]

Those numbers in the Wikipedia chart are the maximums that can be used given all the combinations of mandatory and optional formats. How much space each of the audio and video formats take up on the disc will vary with the compression codec and its settings. I don't know the exact breakdown but so much is allocated for video and so much for audio.

To give an absurd example, say the disc capacity was 10 MB and the audio formats were raw PCM and MP3. In that 10 MB of space I can store (roughly) 1 minute of 2 channel audio in PCM format or three 3 minute MP3 encoded songs at 128 kbps or two 4 minute MP3 encoded songs at 192 kbps. So that is the relationship between the storage available on the disc and the bitrate of the data.

Now we have to actually transfer that data over a wire and that requires some communication protocol which transmits more than just the actual data. The protocol, HDMI in this case, needs far more bits than just the actual data. I can't give a good concrete example because I'm not familiar with the actual data format it uses but just think about all the stuff it does at once - audio, video, control signals, exchanging encryption keys with the sink device, etc.

Yes. However, there is a huge difference between 50Mb/sec and the multiple Gb/sec rate discussed, a 20X-60X and more factor??? You need 20X-60X more bits of protocol to transfer the info bits???
I just have a hard time with those numbers.
Where do the on board processors come in? If you send the bitstream from a CD, aren't those bits are all on the CD itself and is sent at a bitrate of whatever? And, wouldn't the CD capacity of so may Mbits, like 700Mb, includes all those info bits as well?

If so, then the hi-def DVDs, whether 30Gb or 50Gb is it, includes all the info bits, no? And if you must transfer at say 1Gb/sec, that doesn't take too long, does it?
Do you see where my confusion is coming from?

 

[farscaper]

There is enough marketing crap (spin) being said about speaker wires that I can't even imagine the marketing spins the 1.3 HDMI cables and interfaces are going to have.

 

[davidtwotrees]

Thanks, Clint. Once again you guys hit the article perfectly on the head. It wasn't to technical. When the article gets too tekkie, I usually lose interest and don't finish. This one was spot on and made a complicated issue fairly simple.
As someone who has no hdmi connectivity, (I think my denon 3910 has a port), I am mildly interested in the topic. For someone like myself, who has all his components on one wall close together, my hdmi runs will all be under 5 meters if I purchase gear with hdmi ports in the future, and much of this will be a non issue for me and many other gear heads here.

So, thanks for the great article. It seems to work well where you keep it somewhat simple in the article, and let the tekkies go deep in the forum posts. Excellent. Most Excellent. D2T

 

[Alamar]

Oh just wait until part 2 which goes into the rather unbelievable practices of one of the main companies behind HDMI. It will be absolutely eye-opening.

I know I wasn't the target of the comment but thanks for the heads-up. As a newb anything that I can find out about the real workings of what's going on is helpful.

************* To avoid the double post ******************

@MDS:

No HDTV is 1080i. All HDTVs are progressive scan. 1080i may be the highest resolution it can accept as an input but it will always scale whatever is input to its native resolution. So if this tv 'upconverts' to 1080p then it IS 1080p - its native resolution is 1920 x 1080p. It just cannot accept a native 1080p signal as an input.

Being a newb I'm a little confused by that.

Are you saying that the older RPTV 1080i sets are not HDTV or are you saying that they are really basically 540P?

******************************************************

How does this mesh with the hi def DVDs max transfer rates of 36 or 54Mbits/s?
Isn't this the transfer rate going through the cables? A bit of difference between this and the Gbit rate in the article.

This isn't exactly right but you could think of the data transfer on the Hi Def DVD being how fast the player can read from the disk. This is the 30-50Mb/s number that you mentioned.

The data on the disk is highly compressed / zipped. The signals that the Hi Def DVD player sends out are uncompressed which is why the Hi Def DVD player sends out MUCH MUCH more data than it actually reads.

Basically the Hi Def DVD is zipped and what your TV gets is unzipped. This explains the big difference in data rate and total data over time.

 

[MDS]

IBeing a newb I'm a little confused by that.

Are you saying that the older RPTV 1080i sets are not HDTV or are you saying that they are really basically 540P?

No, I'm saying there is no such thing as a 1080i TV. A fixed pixel HDTV has one single resolution and always scans progressively. If the TV has a native resolution of 1366 x 768 but can accept 1080i (1920 x 1080 interlaced) people often say they have a 1080i TV, but in reality it is a 768p TV that happens to accept a higher resolution as input.