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I am required by a distance education language course to record some audio and submit it. However, they are being absolutely unreasonable. I am only allowed to attach a file that is 5mb while my recording is 17mb. Even after zipping, the file still exceeds the limit. I cannot host it on my site and provide a link either. I have tried breaking up the files into part files with 7zip but they refused to accept it. Any ideas?

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5 Answers 5

up vote 7 down vote accepted

a WAV file is lossless, uncompressed audio. even with a lossless, compressed file format like FLAC, you probably won't be able to get it within the constraints.

you should try a lossy format like MP3. generally, a high quality MP3 file is indistinguishable by the human ear from a lossless file. if you're on Windows, you should try a program such as winLAME, if you're on OS X, try XLD. alternatively, Audacity with LAME will run on any operating system.

if the file is still too big, you may have to lower the bitrate.

EDIT

if it is absolutely crucial that the file must be a .WAV, there is a way to reduce file size, although you may lose quite a bit of quality. download Audacity and open your file up in it. first, try going to "Tracks > Stereo Track to Mono" go to file > export, and save it to a new location. if this doesn't help, then in the bottom left corner, there is a dropdown box for project rate.

project rate

use the dropdown to change this to a much lower value, then try exporting again. this should drop the filesize considerably, though in this case quality is much affected as well.

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You could also just use less sample rate or bit depth for the PCM audio. –  slhck Aug 3 '12 at 8:38
    
Or use Opus, a free audio format that's currently the best at everything but lossless encoding. –  Cees Timmerman Dec 31 '13 at 1:06
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I would suggest compressing your WAV as an MP3 instead. MP3 is an audio-specific compression format, whereas ZIP is a more general-purpose compression method. Because ZIP is general-purpose, it is less suited to the specific task at hand of compressing audio.

The MP3 compression algorithm is designed specifically for audio, and is a "lossy" algorithm and thus can compress audio far better than ZIP can. ZIP uses a "lossless" method and is thus forced to preserve each and every bit in the recording verbatim, taking up more space in the resulting compressed version.

Even though compression for MP3 is "lossy", such information loss isn't likely to affect the perceived quality of a voice recording at all, provided you compress your WAV file at, say, an MP3 bitrate of 128Kbps or higher.

Your distance education language instructors should be able to deal with an MP3 audio file (MP3s are incredibly common nowadays) but check first to make sure this is an acceptable solution for them.

If compressing using MP3 or another audio-specific algorithm isn't acceptable, you could reduce the sampling rate or other parameters in your WAV recording. If you are recording at 2-channel (stereo), 44KHz, 16-bit, for instance, the file would be larger than if you recorded at, say, 1-channel (mono), 22KHz, 16-bit. etc. Play around and find out what is acceptable for your voice recording.

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First I would recommend you convert it to mp3 or wma, but these courses seem to think that wav is the holy codec and will accept nothing else (been there, done that).

So I would say just look for a compressor, a quick Google search came up with this. But I can't comment on it, since I've never used it.

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It is throwing an error. "Unsupported 16-bit application". –  Nyx Aug 3 '12 at 1:32
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Does it need to be a WAV file? You could maybe compress it by encoding it as a FLAC (lossless) or Vorbis (lossy %%) file. If it has to be WAV, someone on stackoverflow.com seemed to think that Audacity might be able to reduce the size. I assume that would involve setting a different bit rate/byte rate/whatever it is when you export the WAV file after importing it.

%% You might be able to pull off a lossless Vorbis file, but it probably wouldn't actually compress the data, so it's really irrelevant.

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They weren't kidding about this kind of stuff. They want it according to their specifications. I tried hosting it on my site and sending a link and I got a warning from them. –  Nyx Aug 3 '12 at 1:29
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You can give a try to speex. It's main goal is to compress speech: http://en.wikipedia.org/wiki/Speex

Its container is ogg, which is widely supported.

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