Scratch

I recently started making a project that would help me learn my lines for a play. This is the first time I've used this Scratch feature and I ran into the same problems that a lot of people have had. I'm a musician and have many years experience working with pc audio so I figured I'd give some pointers and explanations. These are just my thoughts so I could be wrong, of course.

1) The Recording meter
When you begin recording a sound in scratch, you get the visible audio meter. What it is showing is the volume of whatever sounds are being recorded. (More on improving that later.) Basically, the louder the sound, the higher the meter jumps to the right, eventually turning from green to yellow, then red if I remember correctly.
The ideal situation is having the meter top out just where it goes from green to yellow, or possibly from yellow to red. That means you are getting a good, loud input into Scratch that should result in a better recording. Good luck on getting that! I'll explain why in a bit.

2) All microphones are not made equally. Nor are all sound cards. Nothing Scratch can do about that. But be careful, there are 2 inputs usually to run a mic into. One is called the Mic input and the other is called the Line-In input.  Surprisingly, the Mic input is usually not what you want. It is typically very noisy or generally low quality and recorded sounds will suffer.
The Line-In input is the correct input to give you the nice, clean recording that you want. BUT... (isn't there always a "but"?)

3) The Line-In input is a low level input. Line level signals are handled at a very low volume (voltage) and must be pre-amplified to be made loud enough to get a loud, usable audio recording. This can be very tricky so I DO NOT RECOMMEND doing this on your own, even if you have the right equipment because if you get it wrong, you can fry your soundcard and possibly other parts of your computer...
I have a crazy guitar amp (not made anymore) that has all kinds of digital processing built into it and gets really loud (around 100 watts stereo.) Long ago, I made a patch specifically for running a microphone into it instead of a guitar. The trick to running all that into my computer is to start with the amp's volume all the way down and while recording in Scratch (or any app,) slowly turn the amp up until I get sound being recorded. Then I fine adjust the volume level and distance from my mic until I get the sound meter up high enough to get a good recording.
This will vary because as you get closer to the mic, or simply talk louder, the level will go up on the meter. If it goes too high (up into the red, especially at the top of the red) you will get what is known as clipping. Think of it as there is only so much room in a wave file to hold digital audio data. Try to put too much and things get nasty sounding and craziness begins to occur. You NEVER want to hit the top of the red in any meter. In audio terms, more volume means more voltage. If you send too much voltage into your computer, components will fry and things will stop working as smoke comes out. I've actually done this to a $1500 guitar amp once, it will ruin your day to say the least. The guitar amp I use for recording has a selectable compressor that helps me keep my sounds from being both too quiet and too loud, cool feature!

4)  What is with the pops, clicks, and missing sound parts? From what I can tell, Scratch uses a built in, non-configurable compressor to try an compensate for weak audio input signals. A novel idea but since it cannot be tweaked, it is very hit or miss, usually miss. In case you missed it earlier, a compressor can do many things but is typically used to make soft sounds louder and loud sounds softer. Watch a good singer on stage (like the dude from Incubus) and notice how they are constantly moving their mouth up close to the mic sometimes but on louder, yelling type parts they pull the mic back farther away from their face. Besides singing softly or loudly, even different consonant sounds (P, K, S, etc) are louder or quieter than others.
Sounds are made, literally, by vibrations traveling through the air. We make the sounds by forcing air through our body and shape it ultimately with our mouth and lips. Different shapes mean different amounts and strengths of air coming out. So that singer who is working that microphone back and forth is actually doing a sort of compression by hand.
That is also why when you see people in a recording studio, they often have weird, round thingees in between themselves and the mics. These are called windscreens and they allow sound to go through while regulating the air pressure that actually hits the mic. Very necessary because pro recording mics are super expensive and super sensitive while stage mice must be super rugged because they are gonna bounce off of floors and groupie heads, etc. You can make a great windscreen yourself out of a wire hanger and some pantyhose. This also helps keep spit from ending up in your mic which can/will eventually degrade the sound.

Back to Scratch.. Scratch uses its built in compressor to try to compensate for all these crazy factors but in the end, most people are probably getting a very weak (barely green) audio signal at best. So what happens is, as the compressor tries to adjust the sound levels, digital glitches are created and this is the ugly popping noises that seem to come from nowhere.
As for missing audio portions, Scratch has another compensating feature since you cannot edit recorded sounds. To try and make sure that there is no dead (silent) portion to your audio both at the beginning and at the end of your recording, Scratch automatically cuts off the beginning and ending silent parts. This is kind of handy BUT if your recording level is (typically) low, even though there is sound, Scratch cuts off part of it. My experience has been that it is worse about cutting off the end of a file rather than the beginning. Just consider it a sign that your recording level still needs to be adjusted to louder but remember to always make several small adjustments rather than one big one to avoid letting the smoke out of your equipment.

So... you are better off using another piece of software to record your sounds to avoid the pitfalls of Scratch's native compensation features. Another advantage is that with most software, you can go back and see and edit your recorded .wavs to ensure that they meet your own specifications before importing them into Scratch. You will also want to convert them into .mp3s first because .wavs are huuuuge. When converting into mp3s, make try making them at a bit rate of 128kbps. Higher bit rates mean better quality but bigger files. You can go lower but your audio quality will gradually become reduced. I don't know the exact kbps range that Scratch accepts but I suspect that using too low (or high) a bit rate is the cause of most "Scratch won't use my mp3" problems. Some programs also let you create variable bit-rate mp3's which might be great outside of Scratch but have potential to fail in Scratch so avoid that option.

Or, if you have an amplifier, decent mic, a compressor, decent sound card, and years worth of recording experience, you can make the Scratch recording interface work fairly well. Lol. Of course the Scratch Team doesn't expect that, hence the compensating features built into Scratch.

One more tip, I almost forgot. Just like the way that you can adjust the playback volume for your pc, and separate functions (such as midi, .wavs, Line-In, etc) you can also adjust the recording level of various inputs (.wav, Line, etc)
Of course this will vary depending on who made your sound card, etc. but usually you can see and adjust this by double clicking the speaker volume icon on the right end of your Windows Taskbar. The pop up window defaults to volume and mute settings for playback. Selecting Options/Properties/ Recording will switch the window to the adjustable recording levels for various features. Make sure that your Line-In recording level is at or near the top. If you must use your Mic input, do the same with it. You may need to go back and tweak it some, such as turning it down if your recorded audio has excessive noise in it. Kind of like when the audio meter goes too red.