Can no longer export to MP3

[yanko]

At some point, not associated with any specific action on my part that I can recall, I stopped being able to export to MP3: It appears to work but the file produced is 1k long and is invalid. No error messages given. The first time this happened I was running 1.2.4. I uninstalled everything and installed 1.2.6 with the latest LAME dll. It worked for a month or so and now it's back to the old behavior, once again, for no obvious reason. I cannot get it to work again. Anyone else have this problem? Any suggestions? I'm running XP SP2.
Thanks!
Yanko

[Gale Andrews]

Almost certainly you are exporting at a bit rate that is not compatible with your sample rate. Set the Project Rate bottom left of the Audacity screen to 44100 Hz. More explanation:
http://audacityteam.org/wiki/index.php? ... l_not_play

[kozikowski]

Sudden, unexplained Windows insanity can be caused by Windows trying to update itself in the background. Do you have that option enabled? I personally make Windows warn me and then I'll do the update manually. I don't like surprises. The other obvious problem could be a virus or other malware. When was the last time you did a comprehensive system scan? Most virus software will not do that without the user because it takes the machine out of service for sometimes as long as an hour or so.

Did it happen on a Tuesday?

"When necessary, Microsoft provides a new security update on the second Tuesday of each month and publishes a bulletin to announce the update."

I don't think it's a defrag problem, but you could be running out of hard drive space. That creates all sorts of problems.

Koz

[kozikowski]

<<<More explanation:>>>

That's.......not clear.

We rarely do anything at 44.1 because we're basically a video shop. How do the Audacity Project Preference rates relate to the rates as changed on the timeline and further relate to the MP3 encode rates? If we pick 48/16, does that mean certain MP3 exports become unavailable to us? Does is say that at the time of export? Does v1.4?

We have found that we can create all sorts of damage by changing the numbers on the timeline.

Koz

[yanko]

Hi, thanks for your help. It must have been the rate mismatch: I think I must have had a project rate too low for the MP3 bit rate. I had not noticed that the track and the project can have different rates. Although, if i remember correctly, it wouldn't work even at the lowest mp3 bit rates.

For someone who does not record at very high quality, what should I use as a default sample rate and depth?

Yanko

P.S. I don't let windows update without my knowledge and I do do regular virus scans.

[Gale Andrews]

Yanko asked: "For someone who does not record at very high quality, what should I use as a default sample rate and depth?"

It entirely depends what your objectives are and what your end product is. All recording in Audacity is at minimum 16 bit. If you want to a lot of editing on the recording then 32 bit is much preferable if you have the space it requires. If you are going to end up exporting a 16 kbps MP3 for internet distribution then you may well feel that 22050 Hz or a little lower is enough. It almost always will be good enough for many speech recordings. If you are recording music, especially with instruments, 22050 Hz isn't high enough to capture all the audible frequencies up to around 20000 Hz that there will be, because any sample rate only captures frequencies at half that rate. So for music you preferably want to record at the highest "native" rate your card offers (i.e. a real rate, not one it claims to support but only does so by resampling it to another rate).

Koz : "We rarely do anything at 44.1 because we're basically a video shop. How do the Audacity Project Preference rates relate to the rates as changed on the timeline and further relate to the MP3 encode rates? If we pick 48/16, does that mean certain MP3 exports become unavailable to us? Does is say that at the time of export? Does v1.4? We have found that we can create all sorts of damage by changing the numbers on the timeline.

By timeline, I assume you mean the Project Rate dropdown bottom left. The Project Rate affects recording, playback, mixing and export. If you are exporting MP3, the format specification only allows certain combinations of sample rate and bit rate (those listed in green at http://audacityteam.org/wiki/index.php? ... l_not_play )

44100 Hz is recommended for most users because of its near universal support on players, and because (in 1.2.6) that rate will work with any bit rate even if it's a combination not on the green list. 48000 Hz will also work with any bit rate in 1.2.6. This happens because we let LAME downsample to an appropriate rate if your sample rate is too high for the bit rate. Example: set your Project Rate to 48 000 and 16 kbps MP3 export bitrate in Preferences. That's an illegal combination, but if you look at the exported MP3 you will see the sample rate has been downsampled to 16 kbps. On the other hand if you choose a low Project Rate e.g. 22050 Hz with a high, illegal 320 kbps MP3 export bitrate, you will get Yanko's problem if you use 1.2.6, a useless small file, because LAME does not upsample to something legal. So in the Beta (and in 1.4 when released) Audacity simply tells you if the sample rate/bit rate you chose won't work and offer you the highest legal sample rate. Note however with low bit rates, the quality is often better with a somewhat lower sample rate than the highest legal one. This is because there may just not be enough bits to perform the calculations properly with a higher sample rate.

Gale