Recording too fast

[rjcritter]

I first want to say that I've been using Audacity since about 2004 and it is a wonderful program. Every version I have used has been very useful no matter what I was recording. I have never had any major issues with Audacity until the past week. So I would like to give a huge thanks to everyone behind the program.

I'm using version 1.3.7. The problem I've been having has to do with the recording speed. I host a radio show at our business 6 days a week, one hour a day. I used to stream over the internet to the stations using Window Media Encoder. I never had a problem when WME was running. But now I have went to SHOUTcast Source. Ever since, I can record my hour long program and instead of being exactly one hour with Audacity I'm more like one hour and twenty seconds. I know this doesn't sound like much but when you are recording in a time frame the last song I play gets cut off and the file has to be longer to get it in. I am trying to reserve as much space on my hard drive as possible. I have tried to adjust everything I can think of in Audacity (sample rate, sample format, converter, dither, etc.). Nothing seems to change the problem at all.

The only possibility I can think of is maybe I have a plug-in with WME that allowed Audacity to run at a "real time" rate, and now that I'm not using WME it's recording too fast. Please help in any way you can. Again, this is a wonderful program that has come in EXTREMELY handy for me in the past. Keep up the good work and I hope to hear back soon.

Thanks

[steve]

I suspect that the problem is with your sound card.
Sound cards use an internal "clock" to regulate the sample rate - problem is that most non-professional sound cards use one clock for recording and another for playback. If the clocks do not match exactly (which they never do) then the playback rate will be slightly faster or slower than the recording rate. Usually it is close enough to be OK for the average user.

The problem can be greater if you are using different audio devices for playback and recording, and in your case, streaming the recording may be using the computers internal clock rather than the one on the sound card. If you are using an inexpensive sound card you may find the problem disappears if you upgrade it (sound quality will definitely improve).

[rjcritter]

Thank you for the great ideas on your reply. Once I think about it that makes alot of sense. My next question though is how do I change the internal clock(s) in my sound card (if I even can)? I'm using an "SB Live! 24 bit" sound card which I thought was very good quality. (Any recommendations on a sound card?)

[steve]

how do I change the internal clock(s) in my sound card (if I even can)?

You can't - it's built into the hardware.

I'm using an "SB Live! 24 bit" sound card which I thought was very good quality.

Yes they're not bad - one of the better "consumer grade" cards (I've got one myself), but then we're only talking about a 0.5% variation in speed.

now I have went to SHOUTcast Source. Ever since, I can record my hour long program and instead of being exactly one hour with Audacity I'm more like one hour and twenty seconds

Tell me about this - I've a rough idea about the basics, but it's not something I've ever dabbled in. I'm interested in your working method and what bit of hardware is doing what at each stage in the process.

[rjcritter]

I'm using winamp to play my music to a control board where I have my music and my mic plugged in. The control board in turn sends it back to the sound card. All my volume on the input is turned down except for the line-in, which I have set as input on Audacity (play through turned off). That way I don't have a constant feedback. All SHOUTcast Source is is a plug-in for winamp to stream all my sounds through the line-in to either a dnas program (which I'm actually still learning about) or an outside hosting company that I am currently using. Either of these actually streams the program to the internet. That's pretty much it.

The only thing that you have to remember when doing your own stream is that your isp MUST be high enough upload bandwidth to stream to several people at once. If you only stream 24kbps and you have 768kbps upload, you can stream to 30 people at once comfortably. The only problem is you are sacrificing quality to allow more streams at once. On the other hand if you stream 128kbps (CD quality) and you have 768kbps upload you can only accommodate 6 listeners at best. Like I said, I'm still learning alot about doing internet radio. I enjoy doing the show and I only have to stream to 2 stations at once. But I'm afraid I may be getting a little over my head with the internet radio thing (about $300/month for a T1 line over my head)!!!

I hope that answered the question you had. Sorry if I'm long winded. By the way, I don't suppose you have any suggestions on how to eliminate the problem I had with recording in 1.3.7? I know it's probably dumb to worry about 20sec of excess recording in an hour show, but I was used to it recording EXACTLY one hour. Oh well, beggars can't be choosy. Thanks for listening and again, love the program.

Critter

[steve]

No worries about being long-winded. Detail is good, it helps to create a clear picture.
This all sounds interesting, and I think that I get the gist of it, but I don't quite see where the "60:00 vs 60:20" comes in. Is part of the show pre-recorded and part live?

[rjcritter]

No, it's all live. I have a timer set to count down 60 minutes. As soon as I start my intro song I start the timer. I only start Audacity 2 sec before I start the show but I always delete the silence. I do it the same way every time. That's what I don't understand. When I use WME everything comes out exact. When I use SHOUTcast Source it's a little longer by the time I get to 60 minutes. The radio stations give me exactly one hour and no more. It's almost like there's something inside of the WME program that overrules the sound card's internal clock.

I guess I'll let you know now that I went back to WME because SHOUTcast Source has been giving me even more problems than just the ones with Audacity. I would love to use it but it keeps dropping the stream during the broadcast. Well, maybe that's something for you all to investigate. Why does WME allow Audacity to record at a different speed than normal? Albeit only 20 seconds difference, it's still something to ponder.

If you need any more info I'll be more than happy to help. Just keep on posting.

[steve]

I do it the same way every time. That's what I don't understand. When I use WME everything comes out exact. When I use SHOUTcast Source it's a little longer by the time I get to 60 minutes.

So your live show IS EXACTLY 60:00 (your stop watch is accurate), but when you play back the recording from Audacity, the recording is 60:20. Have I got that right?

If so, then it certainly sounds like the clock issue that I spoke about earlier. I've never used my SBLive for recording more than a few minutes, so I can't say whether that amount of discrepancy is "normal" for these cards. One thing that does occur to me however - I think that Audacity 1.3.7 on Windows supports "Direct Sound" as well as MME and WDM drivers. If you look in "Edit menu > Preferences > Audio I/O" you should see several device options for recording and playback. It may be that with your new Shoutcast set-up you are using a different driver model from what you were using on your previous set-up.

Make a note of your current driver settings (so that you can go back to them if you break something) and try the Direct Sound option (if you are already set to that, try the normal WDM drivers). As you say - it would be nice to know the cause of this issue.

[rjcritter]

Yes. You are correct. I have twenty seconds extra when I don't record with Windows Media Encoder.

I have already made it home for the night but I will check my settings on my computer when I get to work tomorrow. I took a peek at the settings on my home computer and there are some new options on the Audio I/O I never noticed before. Maybe Shoutcast installed them when I installed the dsp program. I'll do some more experimenting when I have time at work and let you know what I come up with.

Just so I know, tell me the difference with the MME options I'm showing and the DirectSound options. I know very little when it comes to sound cards and the different hardware/software that keeps them running properly. I know how to adjust the basics but that's about it.

[steve]

Just so I know, tell me the difference with the MME options I'm showing and the DirectSound options. I know very little when it comes to sound cards and the different hardware/software that keeps them running properly. I know how to adjust the basics but that's about it.

I'm no expert either. This will explain better than I can http://en.wikipedia.org/wiki/DirectSound