HDMI Understanding

[AVlover]

Hello Experts,

I think this is my first post after I joined HIFIVision few months back. I am trying to follow most of the greatly helping posts and expert opinions.

In near future I will be looking for a good entry level HT system to replace my 10 years old audio system.
But wanted to understand few things about HDMI/digital formats before I start any search:

I am trying to write my understanding as brief as possible, because every concept in AV can be extended as much as possible.
I am just trying to touch base the basics:
1. when we say complete analog recording and playback it is mostly a magnetic media and 2/4 tracks.
2. Now a days because of digital world, there are many different technologies emerging, but till HDMI, the recording format was some sort of data compression which can cause data losses, HDMI is uncompressed so Hi Definition, is it correct .....?
3. Another question arise in my mind is like, when we say 5.1 or 7.1 format, it is that the digital signal is recorded in those many number of channels/tracks, hope that is correct .
4. So if I am recording a video or audio in 5.1 format, as it is a fresh new thing I can decide what will go in which channel and the audio can be in synch with video which is getting recorded.
5. My query here is, with the new devices when we uplink/convert any old or analog or legacy video or audio track in HDMI and 5.1 format, what is used as the basis to make the audio split in those 6 channels ....?

I think these basics will help me to understand how to enjoy converted tracks in new technology.

I am basically a music lover and I think I have good ears ...., hope I will get many helpful replies

Regards,
AVLover

 

[venkatcr]

1. when we say complete analog recording and playback it is mostly a magnetic media and 2/4 tracks.

The original recording is always done in analogue, though it may be converted immediately into digital for storage. The number tracks depends upon the producer and the editor. For example if you take a live show, there may be 10 or more mikes, each of which records a single mono channel. These channels are then mixed in the studio as the producer wants. Generally movies are mixed into either a 5.1 or 7.1 mix, while music is mixed as stereo or 2 channels. There are some music that have also been mixed as 5.1.

2. Now a days because of digital world, there are many different technologies emerging, but till HDMI, the recording format was some sort of data compression which can cause data losses, HDMI is uncompressed so Hi Definition, is it correct .....?

You are confusing recording, storage and transport mechanism. Recording and storing of uncompressed data has been available to the professionals for a long time. It is just that such recordings could not be distributed commercially because of limitation in media (CD/DVD/VCD etc), and the transportation mechanism. S/PDIF has a bandwidth limitation and can only carry so much data.

Blu-Ray has removed the media limitation to a certain extent while HDMI, as a transport mechanism, has removed the transportation limitation.

3. Another question arise in my mind is like, when we say 5.1 or 7.1 format, it is that the digital signal is recorded in those many number of channels/tracks, hope that is correct .

Actually movies could be recorded in as many as 15 or 20 channels of sound. The editor then listens to each channel and mixes it as 5.1 or 7.1 to give you the best effect.

4. So if I am recording a video or audio in 5.1 format, as it is a fresh new thing I can decide what will go in which channel and the audio can be in synch with video which is getting recorded.

At a professional level, movies are recorded with a single mike in the camera. This sound is usually discarded. The actors then speak their part in a studio, the musicians then play the music, the sound specialists then create the sound from recorded channels, and all this is carefully mixed by the editor. Usually, for music, the video is played on a screen which the music director watches, and then composes and plays the music. Songs, if any, are recorded separately before the scene, and then played for the actors to lip-sync. That is never used in the movie as it will be very noisy. What is used are all studio recordings.

5. My query here is, with the new devices when we uplink/convert any old or analog or legacy video or audio track in HDMI and 5.1 format, what is used as the basis to make the audio split in those 6 channels ....?

As I said before, the two people who are the most important are the producer/director and the sound editor. It is these people who decide what you hear. The director visualises a scene which he narrates to the sound editor, The sound editor either takes the sounds recorded, or creates new sound that he mixes. You will be surprised to learn that many of the sounds that your hear were never recorded but taken from stock sound that is available to professionals.

Cheers

 

[AVlover]

Hi Venkat,

Thanks for your explanation, I could imagine most of the things.... but what I was interested in mainly was.. like the HTIB devices I am screening do have some provision to convert a normal audio or video input to HDMI. As the system is basically 5.1 it may also convert them into the 5.1 format.

Suppose I have an old cassette player and I connect it to a HDMI converter, how it converts into HDMI will there be any upgradation in actual audio ....? or it will be still stereo and with almost same audio quality, only change would be the response of the better speaker system

From your response what I could get is because of HDMI conversion there may not be a very great change in the original track and it will not be converted into true 5.1 but it will still remain the basic stereo, isn't it ....?

Regards,
AVLover

 

[wlg]

What you say seems to be right. If the media CD/DVD/HDD etc being played is recorded in 5.1 and played thru a 5.1 HTB , only then can true 5.1 be heard. Playing normal DVD's all 5 spkrs will be heard but no true 5.1 effect

 

[Subcenter2009]

Dear Friend,

One can get Dolby Prologic IIx/z by connecting analog line level inputs of the tape deck (Usually L-R RCA cables) to the analog inputs of an Audio-Video Reciever more commonly known as an AVR.

For that matter, One can also connect a LP Record Player (Turntable) to the AVR to get the same Prologic II effects. The voice is usually rooted to the center channel loudspeaker if one chooses to use PL II.

Prologic is an Analog Technology where 2 Channel audio is sort of matrixed to get convincing surround sound..

I am not an expert on this topic.. Maybe the experts who contribute regularly can clarify.

Thanks,

Subcenter2009

 

[no1lives4ever]

Typically the HTiB and AVRs only convert video signals to HDMI. The audio signals are played by the AVR itself.

-- no1lives4ever

 

[venkatcr]

There have a been replies, but let me try to clarify this.

but what I was interested in mainly was.. like the HTIB devices I am screening do have some provision to convert a normal audio or video input to HDMI. As the system is basically 5.1 it may also convert them into the 5.1 format.

HMDI carries two sets of data. One is audio (upto 8 channels) and the other is video.

Assume the following connections:

1. DVD to AVR - Analogue composite/component
2. Tape deck to AVR - analogue audio (usually called L&R)
3. AVR to TV - HDMI

In the first scenario, let us first assume you are playing a CD. A CD has both audio and video information. The video information is just name of the track, artists, playing time, etc. This is sent AS IS without any conversion to the TV through the HDMI cable. The audio part is processed by the AVR and sent to the speakers. No audio is sent to the TV.

Now let us assume you play a DVD. DVD has video data as well as upto 6 channels of audio. There are two things done to the video data - one is called upconversion where the video is converted to digital format for transmission through the HDMI cable. Some AVRs also do what is called upscaling where the resolution of the video is scaled upwards to upto 1080P.

The audio is processed internally by the AVR and sent to the speakers.

In the second scenario, the tape deck is primarily an analogue device. This does not send any video data. The audio, in analogue form, is just amplified by the AVR and sent to the speakers. NO data is sent to the TV.

You cannot connect an analogue source such as a tape deck through or to an HDMI as the source device does not have an HDMI socket.

Suppose I have an old cassette player and I connect it to a HDMI converter, how it converts into HDMI will there be any upgradation in actual audio ....? or it will be still stereo and with almost same audio quality, only change would be the response of the better speaker system

At the outset, you cannot connect a cassette player to an HDMI converter as there is no HDMI socket in the player. If you are talking about connection through analogue audio cables to the analogue in of the 'converter', the converter will do nothing. What you will get is just simple amplification of the source material. There is no conversion whatsoever.

From your response what I could get is because of HDMI conversion there may not be a very great change in the original track and it will not be converted into true 5.1 but it will still remain the basic stereo, isn't it ....?

Unless an audio data comes recorded in 5.1 or above, it cannot be converted to 5.1 by any device at home. You can of course use some some software such as Audacity and convert stereo to 5.1, but for this you have spend a few hours for each song.

What AVRs do is something called Neo or Pro Logic. Essentially, Neo/Pro takes a stereo or mono audio data, and simple plays it on all channels. That is it. Actual 5.1 means having different voice/instruments being played on different channels. This can never be done by any logic and has to be done in the studio. What Neo/Pro also do is build in a few millisecond delay in some channels making you feel you are getting surround sound. It is not surround sound, but just delayed audio.

Cheers

 

[gdhiraj]

Hi Venkat,

Thanks for your explanation, I could imagine most of the things.... but what I was interested in mainly was.. like the HTIB devices I am screening do have some provision to convert a normal audio or video input to HDMI. As the system is basically 5.1 it may also convert them into the 5.1 format.

Suppose I have an old cassette player and I connect it to a HDMI converter, how it converts into HDMI will there be any upgradation in actual audio ....? or it will be still stereo and with almost same audio quality, only change would be the response of the better speaker system

From your response what I could get is because of HDMI conversion there may not be a very great change in the original track and it will not be converted into true 5.1 but it will still remain the basic stereo, isn't it ....?

Regards,
AVLover

HDMI is just a medium to carry ur audio + video signal whatever u feed in is what u will get out - AVR can do DSP to simulate multi channel sound for you which is not 5.1 but u hear sound from all 5 speakers so at times it sounds better.

Can u explain what u have in mind when you say "HDMI convertor" ??

 

[prankey]

A CD has both audio and video information. The video information is just name of the track, artists, playing time, etc. This is sent AS IS without any conversion to the TV through the HDMI cable. The audio part is processed by the AVR and sent to the speakers. No audio is sent to the TV.

Venkat - Allow me to clarify few things here. CD do NOT contain ANY Video Data! It only contain POINTERS to different tracks. Only CD TEXT contain the Track Names (again, its not Video). Typically a CD player do not have HDMI output unless you have a recent DVD or a BR Player.

Now let us assume you play a DVD. DVD has video data as well as upto 6 channels of audio. There are two things done to the video data - one is called upconversion where the video is converted to digital format for transmission through the HDMI cable. Some AVRs also do what is called upscaling where the resolution of the video is scaled upwards to upto 1080P.

DVD's Video is ALREADY Digital and hence upconversion for HDMI will happen only if you are not transmitting through HDMI in DVD's native resolution of 480i/p or 576i/p. Else, there will be NO UPCONVERSION as such. Now when the upconversion occurs, its essentially UPSCALING to 720p or higher HD resolution. So, unless you point me to something, upconversion and upscaling is different name for the same process. As I understand a video from one type of stream can not just be converted to another resolution stream without an upscaling algorithm (otherwise it will essentially look heavily pixellated). I have personally seen pixellation only on some very cheap DVD players when taking output through component output.

Unless an audio data comes recorded in 5.1 or above, it cannot be converted to 5.1 by any device at home. You can of course use some some software such as Audacity and convert stereo to 5.1, but for this you have spend a few hours for each song.

There are several sound cards and free software like AC3Codec which can convert to DD5.1 or DTS5.1 ON THE FLY. Infact such conversion is named as "Dolby Digital Live" and "DTS Connect". Hence there are several cheap or free software available for conversion. Like my Audigy 2 ZS sound card can convert any mono to 7.1 sound coming from a game or movie to DD/DTS5.1 at their max bitrate and my AVR plays them well without any issue.

What AVRs do is something called Neo or Pro Logic. Essentially, Neo/Pro takes a stereo or mono audio data, and simple plays it on all channels. That is it. Actual 5.1 means having different voice/instruments being played on different channels. This can never be done by any logic and has to be done in the studio. What Neo/Pro also do is build in a few millisecond delay in some channels making you feel you are getting surround sound. It is not surround sound, but just delayed audio.

While I agree that we may not get discrete 5.1 to 7.1 audio from PL/PL2 and NEO for a REGULAR STEREO recording, they are not entirely gimmicky! First, they do not simply distribute stereo to 5.1 or so, they do matrix decoding and infact a mono source will essentially output from center channel only. So they do not pass the same sound to all the speakers.

If the Audio was PROPERLY MATRIX ENCODED in PL2 or NEO, they may sound discrete like DD/DTS.

Infact NEO ALWAYS produce discrete sound from all speakers. Check this thread: Pro Logic II or DTS NEO:6? - Blu-ray Forum

Also, the surround sound produced by such processing does not necessarily produce DELAYED output from rear speakers, infact in some of the content and if you set the delay to 0ms, there is practically NO DELAY and what you get from rear speakers are some spacial or phase or ambient sound embedded in the stereo track.

 

[Deepchand]

HDMI The official website has some of the answers.

 

[venkatcr]

So, unless you point me to something, upconversion and upscaling is different name for the same process.

If you look at AVRs, all of them retransmit analogue input data through HDMI to the TV. Many of them including the lower end models from Denon, Onkyo and others do not do any scaling as they do not have the necessary engine inside.

When you retransmit an analogue input signal through HDMI, this is referred to as upconversion. When you take any video input and change it''s resolution, it is referred to as scaling. Information about this difference is available in abundance on the Net, though most people get confused between conversion and scaling terminology.

Cheers

 

[wlg]

I Have a poineer DVD 220KV it does not have 5.1 analogue (RCA) output but has an HDMI cable, manual says 5.1 available thru HDMI, will I get true 5.1 effect when playing 5.1 movies thru ONKYO 3300?
Tks

 

[prankey]

If you look at AVRs, all of them retransmit analogue input data through HDMI to the TV. Many of them including the lower end models from Denon, Onkyo and others do not do any scaling as they do not have the necessary engine inside.

When you retransmit an analogue input signal through HDMI, this is referred to as upconversion. When you take any video input and change it''s resolution, it is referred to as scaling. Information about this difference is available in abundance on the Net, though most people get confused between conversion and scaling terminology.

Cheers

While retransmitting analog PAL/NTSC/HD through component to HDMI, would not it change resolution or digitize regular PAL/NTSC to something like 720p/1080p especially when transmitting HD through changed resolution?

I Have a poineer DVD 220KV it does not have 5.1 analogue (RCA) output but has an HDMI cable, manual says 5.1 available thru HDMI, will I get true 5.1 effect when playing 5.1 movies thru ONKYO 3300?
Tks

HDMI is usually the best way (unless you use some audiophile grade product like OPPO BD players) to digitally transfer 5.1 so you are good with that.

 

[Deleted member 17547]

@Wig: U'll definitely get a 5.1 Audio if DVD is recorded with 5.1 audio

I have a Bluray Player and i am using Yamaha V367 AVR. When i play music thru this player i do get 5.1 audio but that is just recreated by the player based on the sound frequency ranges.

What i understand is that engine in the player seperates the sound for diff channels based on some frequency ranges. Sometimes it sounds gud but sumtimes its not. When i play DVDS or BR Discs i get the true 5.1 channel audio thru my receiver. Here decoder just decodes the sound, specific for every channel and passes that sound to my AVR. Now if i use any DSP or DPro program in my AVR then only AVR will process the sound but generally i use the straight functionswhich just amplifies the sound and passes the sound to different channel speakers.

hope that helps a bit though m not a expert in this..

 

[Deleted member 17547]

@Wig: Check out for Optical Audio Out in your player. If its there then u can also use optical cable to pass 5.1 audio to your receiver. HDMI has advantage over optical cable, as it can pass more than 5.1 channels audio to receiver but your receiver must be able to handle those channels. Plus HDMI can be used for both, audio and video so less cables.

Cheers..!!

 

[venkatcr]

While retransmitting analog PAL/NTSC/HD through component to HDMI, would not it change resolution or digitize regular PAL/NTSC to something like 720p/1080p especially when transmitting HD through changed resolution?

This depends upon the settings in the source and in the AVR.

Cheers

 

[no1lives4ever]

HDMI has 2 parts:

1. Digital Audio - This supports both discrete uncompressed multichannel audio called LPCM and compressed audio like Dolby Digital, DTS, Dolby Digital+, Dolby True HD, DTS HR & DTS MA.

2. Digital Video - This follows the DVI standard used by LCD monitors used on computers and on projectors when using HDMI 1.3. I am not aware of the video encoding method used for HDMI 1.4

Besides this, the HDMI protocol also supports additional channels for the 2 connected devices to query and

Now when you play DVDs/BluRay using a DVD/BluRay player supporting HDMI output, you can send both audio & video to your AVR using a single HDMI cable. You can set the player to either send the compressed audio stream or decode the same and send it as multi channel LPCM streams to your AVRs. In either case, your AVR will play surround audio. In general, you would want your AVR to decode the compressed audio formats to reduce jitter.

Any AVR that supports HDMI audio will decode the audio stream and pass the video stream to the display device over the avr's hdmi output to the display device. There are some AVRs, which are mostly older models, that will only do HDMI passthrough. These AVRs will mostly pass thru the video signals and not do any audio decoding.

-- no1lives4ever

 

[prankey]

2. Digital Video - This follows the DVI standard used by LCD monitors used on computers and on projectors when using HDMI 1.3. I am not aware of the video encoding method used for HDMI 1.4

HDMI v1.4 is similar in many ways to 1.3 where there is NO VIDEO ENCODING (they transfer UNCOMPRESSED video upto 1920x1080p@60Hz)

v1.4 has several additional features like ethernet (LAN) transport, Frame Sequential Full HD 3D support, Audio Return Channel (which in many current TVs is implemented poorly for transporting only stereo audio through this channel from TV to AVR).

 

[AVlover]

Hi All,

Thanks to all responses it has triggered many points to think and understand for me.

Some one asked about my expectation of "HDMI Conversion"
I had an understanding that when you feed an analog audio (I am more interested in audio) Mono/Stereo to a latest AVR, it can convert the analog to digital and then may be have in-built algorithms (Like pre-defined equilisers) to split that converted Digital signal into what ever number of output channels based on human voice range/instrument range or on the basis of frequency and amplitude of audio.

but most of the things are clarified by the responses here and also there are some pointer to grab more information on similar topics


Thanks to all again

AVLover