HD audio for broadcast

Posted: Thu Apr 24, 2008 8:40 am

So after much searching I can't find the answer.

The post house I work for is going to be sending out its first HD commercial.
The whole thing is shot and edited in HD. What I can't seem to find the answer for is: For a HD Dub going to stations is their a digital encoded audio file that should be processed to go along with it? It's not in surround just stereo - is AES 1/2 3/4 all it needs to be?

And if there isn't shouldn't there be?

Posted: Thu Apr 24, 2008 11:45 am

Just bumping the thread. I'd like to see the answer to this as well. Just out of curiosity.

Posted: Thu Apr 24, 2008 4:56 pm

Ya, .. ..
What is HD audio?

Posted: Thu Apr 24, 2008 8:46 pm

HD audio is anything with a bit/sample rate higher than 48kHz/16bit, as far as I am concerned! ha

Posted: Fri Apr 25, 2008 2:19 am

Every broadcaster has differents way of dealing with HD. You should ask them for the right way to go, thay should be able to give you the answer.

Posted: Fri Apr 25, 2008 4:40 am

and some broadcasters will have rules on peak and average levels

even though you have called it AES 1/2 3/4
it might be more correct to think A1 is the first group of 4 and A2 is the second group of 4

SDI - serial digital interface (270 Mbps transfer rate)
SD standard definition
with at least 4 channels of audio ( A1)

HD high definition and the rate gets higher ( up to 540Mbs )
and can contain as many as 4 audio groups ( A1 A2 A3 A4 )

Shocked

err
might be having a brain fade there on the details and data rates
so don't jump on me if I'm wrong

and
TV broadcast can vary and can be mpeg2 or mpeg4
terrestrial ... satellite ... and depending on countries etc

errr
shut up Kev that doesn't matter

HD video with stereo program on audio 1 and 2 of A1 should be fine for the broadcaster to ingest into their system
let them know that you are stereo and NOT 5.1

as niclaus said
" You should ask them ... "
understand their requirments before you submit the material
Cool

Posted: Fri Apr 25, 2008 6:32 am

Thanks for the input. Knowing I'm not dealing with different languages I won't have even considered thinking 4 separate "groups" as you put it Kev. I guess its phone calls to ABC NBC CBS ect.

Now watch every one of them is going to want something different. LOL

Posted: Fri Apr 25, 2008 8:39 am

You see? That's why I love this site. It's like going to school but without the tuition.

Posted: Fri Apr 25, 2008 8:59 am

Found this on another site for surround.

There's several generally accepted channel assignment formats for surround, although the first is fast becoming the most accepted. That is:

1 Left Front

2 Right Front

3 Center

4 LFE

5 Left Surround

6 Right Surround

The broadcast industry has adopted this format for DTV since it easily transfers to four channel digital video media where linear PCM on channels 1 and 2 (as a reference, if required) and AC-3 on channels 3 and 4 are required. Also, these assignments not only represent logical pairings but the pairings used by AC-3 encoding.

Since no one has answered the phone yet. In theory this would led me to think: 1/2 Stereo 3/4 AC-3 encoded.

Well shall see.

Posted: Fri Apr 25, 2008 9:28 am

i more oftenly put PCM on 1/2 and Dolby E encoded on 3/4...

But, again, depends on the broadcaster...

Posted: Fri Apr 25, 2008 11:10 am

I still want to know what HD audio is.?

Posted: Fri Apr 25, 2008 2:50 pm

here in this thread
HD audio is the audio that partners High Definition Video
...
generally to audio herberts, HD Audio might be 96k@24bit or DSD etc
... or better Confused

to follow what niclaus is talking about ... and I agree
" ... PCM on 1/2 and Dolby E encoded on 3/4. "
PCM at 48/16 and is typical with what we audio heads might use
more generally 44.1/16 or 44.1/24
and
Dolby E (think AC3) is a digital stream format which should NOT be thought of as PCM (think mpeg)
BAD explanation Kev
look here
http://www.tvtechnology.com/features/audio_notes/f_tc_audio_notes-06.25.03.shtml
Very Happy

Dolby E can
" ../ accept up to eight channels of baseband PCM audio and metadata and fit them onto a single 20-bit, 48kHz AES pair (i.e., 1.92 Mbps),
OR
" ... fit six channels plus metadata into a 16-bit, 48kHz AES pair (i.e., 1.536 Mbps). "

The PCM audio AND the metadata are output to feed a Dolby Digital (AC-3) encoder.

Do you have the correct meta data and do you have a Dolby Digital (AC-3) encoder ? ... (hardware or software)
Stereo can be put into an AC stream BUT it needs to be tagged correctly.

is any of this making sense ???
Shocked

To Hangman
you said in the original post
" ... It's not in surround just stereo - is AES 1/2 3/4 all it needs to be ? "

that's why I suggested just the PCM stereo on 1 and 2 of A1
don't put any program on 3 and 4 as it could confuse them to think it is a surround Dolby E
...
you could get a very intersting effect

"... I'm not dealing with different languages I won't have even considered thinking 4 separate "groups" as you put it Kev. "
when I said countries ... it was not about languages but about transmission formats and rules ... not just NTSC v PAL but also audio levels etc ... the BBC has some pretty strict rules before they will accept material

the 4 seperate groups are there in the SDI format
A1 A2 A3 and A4 ... each group has 4 PCM audios typically at 48k

Submitting material on a Sony HD Digital Tape may be different to submitting as a Hard Drive File

that is why
...
AGAIN
as niclaus said
" You should ask them ... "
understand their requirments before you submit the material

Posted: Sat Apr 26, 2008 12:08 am

Quote:

The post house I work for is going to be sending out its first HD commercial.
The whole thing is shot and edited in HD. What I can't seem to find the answer for is: For a HD Dub going to stations is their a digital encoded audio file that should be processed to go along with it? It's not in surround just stereo - is AES 1/2 3/4 all it needs to be?

The post house should have received the delivery specs from the commercial's producer.
Should it be encoded?? you need to ask the producer.

Are you delivering files??
Are you going to layback to a video deck?
If so what deck will it be?? Then ask what will the track layout be??
Do you give them PCM audio?? Do you Dolby E encode??
Do you Dolby AC3 encode??

There is no such thing as HD audio.
AES 1/2 3/4 is a label on the back of the digital video deck where audio goes in!!!

Posted: Sat Apr 26, 2008 12:19 am

Quote:

even though you have called it AES 1/2 3/4
it might be more correct to think A1 is the first group of 4 and A2 is the second group of 4

Kev

AES 1/2 and 3/4 are digital stereo pairs that correspond to 2 XLR connectors. The video deck will have 2 XLR inputs one XLR carries 2 channels of audio.

Dolby E for all intents and purposes is AC3, but modified to be a transportable, and editable stream.

Posted: Sat Apr 26, 2008 12:22 am

Quote:

and
TV broadcast can vary and can be mpeg2 or mpeg4
terrestrial ... satellite ... and depending on countries etc

errr
shut up Kev that doesn't matter

What does that have to do with audio?? mpeg is a video codec. Dolby AC3 is muxed into either video stream.

shut up kev Shocked

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