conversion loss rates

[Xerlome]

I'm writing this all over again because it timed out. Thanks for all the good information. I'm exploring what the station players will do. Unless I've missed something, they are audio players, will use audio CDs, and mp3 on flash, and I need to try others, but data and WAV do not work (unless I put about one track of WAV on a CD). Do you think ogg is a good choice for music?

To clarify about conversion loss "calculation": My 192 kbps original file, imported to Audacity, then exported to 320 kbps, becomes 256/2 = 128, which streamed at 128 becomes 64 -- Is this correct(ish)? Does Audacity hold the level at export, or is it the usual conversion effect? The stream is a small percent of listenership. Presumably the air broadcast uses the "128"? Is this a reasonable way for me to technically assess audio loss (ie, besides by ear).

[kozikowski]

(unless I put about one track of WAV on a CD)

And to be crystal clear, Putting a WAV on a CD is different from making an Audio CD. It makes me nervous when you smoosh them together like that. I'm not surprised if the station couldn't deal with a WAV sound file showing up on a CD, but I would be shocked if they couldn't play an Audio CD.

which streamed at 128 becomes 64

It depends on how they do it. Since this is the step where you noticed the degradation, then yes. 64 is the lowest you can go without the music turning to trash, and even then, some people will notice an artifact here and there.

In the early days of MP3 compression, everybody wanted to find out what the limits are, so we all did quality experiments. We got together later and it turns out multiple people all independently discovered 64 at the same time.

The standard export quality in Audacity used to be 128. That was certainly high enough quality for flawless end-product listening, but maybe not post production or re-editing.

Multiple compression passes just kills you.

Koz

[kozikowski]

My 192 kbps original file

How do you know that? I'm sure it was 192 when it got to you, but what was it when they got it?

The multiple compression game is not for the easily frightened,

Koz

[kozikowski]

As another aside, 192 is the minimum acceptable quality MP3 for an AudioBook submission. Stress minimum. Higher is good and we recommend that if possible. Since unless you work at it, you will be compressing a live performance, 192 really is 192. And again, we recommend archiving your work as WAV and only then produce the submission.

Koz

[Xerlome]

"How do you know that? I'm sure it was 192 when it got to you, but what was it when they got it?"

I don't actually know. But the original files I download are usually provided by the copyright holders at 192, and I believe made from original HQ. They are labeled in such a way that they are not easily found using ordinary searches. I believe the providers intend for this minority of users such as me to discover them, so they get exposure without giving the music away to too many people.

"I'm not surprised if the station couldn't deal with a WAV sound file showing up on a CD, but I would be shocked if they couldn't play an Audio CD."

I really meant making an audio CD from a WAV file, but the file is so large I'd need to burn a CD for each track. Or is there a way to make an audio CD from WAV that would accommodate numerous tracks?

[DVDdoug]

I really meant making an audio CD from a WAV file, but the file is so large I'd need to burn a CD for each track. Or is there a way to make an audio CD from WAV that would accommodate numerous tracks?

I'm sure you've notice that most audio CDs have about 10-20 songs? An audio CD can hold up to 80 minutes of audio and up to 1-99 tracks.

If the WAV files are "CD quality" (16-bit, 44.1khz, stereo) the capacity is about the same, but the number of files is virtually unlimited.

Uncompressed 16-bit, 44.1kHz stereo has a bitrate of 1411kbps, so compressed to 192kbps you can hold about 7 times as much music, or almost 10 hours of music on a disc. (If you have album artwork embedded in your files they will be bigger.)

[kozikowski]

Standard Audio CD got that much very high quality music onto one silvery disk by eliminating options. You get one pass of 74 to 80 minutes broken up into as many as 99 songs. You can get close to 80 minutes by having one song. The number of minutes goes down the more songs the disk has to keep track of.

It was intended to replace the vinyl album.

How long is your show? If you have a Friday Evening four hour performance "Weekend Melodies," then it will need to be on four Audio CDs.


That's not the only disk format available. There is DVD-A, the audio-only version of the movie disk. One of the acceptable music formats in DVD-A is roughly the same as an Audio CD, but I can't get anybody to tell me how long the show can be. All the search terms go immediately to super high quality multiple track audio. Nope. Not interested in 7.1 surround, really. Just stereo.

But even that does OK. I got them to admit to 140 minutes, but you have to be able to burn one and the station has to be able to play it.

I know one restriction you're going to run into with this job. Much over about three hours isn't a performance any more. It's surveillance.

Koz

[kozikowski]

Correct me, but from memory, the station doesn't have a production computer, it has a disk player and it can play music performances, not raw files needing production management.

Koz

[Xerlome]

The Program is two hours. I must provide two 58 minute separate continuous segments, to allow for recorded announcements. I can do this on CDs or Flash.

Okay, it is a given that my original audio acquisitions are 192kbps mp3 (or mp4), which I import into Audacity. What WAV do I export from Audacity that will allow up to 80 minutes of tracks on a disk, which I could bring to the station and broadcast from an audio player? In the case of a prerecorded program, I would build each 58 mins. on Audacity with imported 192 files and recorded voice. But how do i export 58 min. WAV that will fit on a CD or play from a Flash. I have not been able to do either.

"Correct me, but from memory, the station doesn't have a production computer, it has a disk player and it can play music performances, not raw files needing production management."

That was true, but now there is a computer (old and very fussy to use), and the players will take Flash. I don't do the long winter drive to produce there, I do that at home. If I use Dropbox to deliver a prerecorded show, I don't need the CD or flash, but the prog.manager doesn't want giant files like WAV. He takes the files as i deliver them and feeds them to the computer to play at the correct time.

[kozikowski]

What WAV do I export from Audacity that will allow up to 80 minutes of tracks on a disk

You don't. It may say 80 minutes on the side of the box, but you never get that in practice. The official maximum is the 74 minutes it says in the standard. It usually settles around 78 or so.

In the case of a prerecorded program

How many different programs have you got?

I would build each 58 mins. on Audacity with imported 192 files and recorded voice. But how do i export 58 min. WAV that will fit on a CD or play from a Flash.

I see from your profile you haven't posted information about your computer. It may be listed back in the history of this thread, but remind us.

If it's old enough, you will need an Audio CD Authoring and Burning Program. If it's newer, Win7, Win8 or Win10, you can author and burn an Audio CD in Windows Media.

File > Export: WAV (Microsoft), 16-bit. That should give you a sound file with exactly the same high quality standards as the CD is going to have. No conversions. I expect the system to give you a 614MB stereo sound file. So that's a good check in the middle to make sure you're doing it right. Windows will refuse to show you the "Dot WAV" extension unless you set Windows preferences that way.

And this is where I sail right off the end of the pier. I'm not a Windows elf. All I got is the CD instructions in the Audacity Manual.

http://manual.audacityteam.org/man/burn ... _a_cd.html

There is one fuzzy rule. Somewhere in the burning program it should ask you to set the space between songs. You won't need that setting (set it to zero), but that's the guarantee you're using an Audio CD program. The others types of CD don't have that setting.

And yes, I totally expect 58 minutes to fit.

Koz