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best way to concentate low-quality mp3s together?
bigidiot
post Nov 19 2012, 00:27
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Hi, there, I recorded an important interview with what I thought was a high quality audio recorder (Marantz).
Apparently I totally messed up on the settings. I used a preset which recorded in mp3 of 64 bit, and worse, the recorder automatically chopped everything into 3 or 5 minute clips. What a bother! (I read the manual very thoroughly after that!)

I need to concatenate the mp3s into a single audio lasting about 45 or 60 minutes. I haven't opened up Audacity yet, but I suspect I can just connect the tracks using that tool. When I put everything into a big track and save as mp3, will the sound quality decline precipitiously? Are there any settings I can take to minimize any degradation of quality which occurs?

This is only speech, so the quality does not have to be great. But there might be some additional sound quality issues (i.e., things which need to removed or flattened out) to deal with.

Should I make a wav of everything first, and then edit and then convert the longer file into mp3?

Thanks. Robert
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Dynamic
post Nov 19 2012, 06:40
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I presume you mean the bitrate is 64 kilobit per second (kbps). This could be pretty good for mono voice, depending on the encoder.

mp3directCut is a Windows tool that does a great job of joining mp3 files together without re-encoding - it takes the MP3 frames and stitches them together. This way you avoid generational loss of decoding then re-encoding. You can even use it to adjust volume or fade-in and fade-out without re-encoding.

Gaplessness: If the Marantz simply encodes the frames then suddenly switches to a new file, you might be lucky that it ends on a frame boundary and carries inter-frame data into the next clip rather than inserting a tiny silence or glitch there.


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Dynamic the artist formerly known as DickD
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AndyH-ha
post Nov 19 2012, 20:47
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The second option of Dynamic's, in case things aren't totally clear, means to just tag those small files with a track number (if they don't come that way from the recorder), put them in a folder, and play them. I use mp3directcut all the time to break larger audio book files into more reasonable pieces. There is never any sign of a problem upon playing the book.

Also, some audio book on CD come with 99 tracks per CD, all short of course. I extract them, tag them, and play them on my personal player. There is never a problem.
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Porcus
post Nov 19 2012, 20:55
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An alternative could be a container? Dump them all into a Matroska?


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One day in the Year of the Fox came a time remembered well
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Dynamic
post Nov 20 2012, 01:25
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QUOTE (AndyH-ha @ Nov 19 2012, 19:47) *
The second option of Dynamic's...


What I was getting at is that is that files made this way will be glitchless when joined in mp3DirectCut with no gap either. If the mp3 encoder is restarted, it begins with padding silence (a necessary part of MDCT used in MP3).
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bigidiot
post Nov 21 2012, 19:42
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Thanks for all your ideas. I'll try them out and report back next week.
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