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Subject:preparing sizable mp3 files for download
Posted by: aelson
Date:5/1/2009 7:24:31 AM
I've been producing audiobooks from a series of oral history interviews I conducted with World War II veterans. I've been putting them on CD but now want to make them available for digital download. I've been converting the files to mp3 and using winzip, but even so the zipped files are 45 to 70 MB and take a long time to upload. I've been converting them at the 128 setting using Sound Forge 7, in the stereo setting. I'm thinking maybe I should do it at 64 and mono. I see a lot of audiobook sites have popped up in the last year with digital download available, and I was wondering if there is any kind of recommended file size or method. Thanks for any advice you can provide. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 7:26:12 AM
Addendum to the above post: Should each track/segment of an audio CD be a separate mp3 file, or should the whole CD be made into one long mp3 track, and if so, how do I go about placing markers to separate the tracks? |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Chienworks
Date:5/1/2009 10:28:23 AM
Just curious ... but haven't we already discussed this a couple times before? :) The choice about splitting by chapter or not is entirely up to what you perceive being best for you and your customers. I've seen them both ways. There are things i like about both ways and things i don't, so it's pretty much a tossup for me. You can insert markers in Sound Forge and these are stored when you 'save metadata with file", however, i don't believe they can be stored in an MP3 file. You'll probably end up with a separate .sfl file that contains the markers. WAV and WMA keep the markers. I'm not sure about other compressed formats. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 12:35:41 PM
Thanks Chienworks! It didn't occur to me that there would be previous threads on this, so I'll try scrolling through to see if I find some. I was reading the post just below this by Wally, and went to listen to his mp3s. Even the good quality ones didn't sound clear, so then I went to listen to a couple of the mp3s I've posted on my web site, and was aghast. There was the same occasional minor but very frustrating occasional garbled sound that was giving Wally fits. I usually post the same audio clip in real player and mp3 (at the 128 rate), and the real player clip was much clearer. I know, I know. Now I've got to do better trial and error testing, perhaps doing the mp3 at a higher rate. Oh well. Any suggestions are welcome |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 12:39:21 PM
P.S. to my post above. When I digitize an audiotape using SoundForge 7, I save it in .wav, realplayer and mp3 format, then use the .wav files to make the CD. Sometimes I make changes to the wav file that aren't on the mp3 file, so when I make mp3s to put up for download, I convert them from the CD. Would it be better to convert them from the original .wav than from the CD? I notice that the CD files are uniformly clipped at the top and bottom of the wave, whereas the wav files aren't. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Chienworks
Date:5/1/2009 3:36:50 PM
Actually, unless someone else is posting using your name, you're the one who's started a couple of previous threads on this topic. ;) I've always had very good luck with SoundForge's MP3 codec. I always set the quality slider to the highest level and let it rip. Often i'll compress speech down to 32Kbps or 24Kbps for minimal file sizes. The voice is still quite recognizable and intelligible at 24Kbps, though it's definitely fuzzy. If you want high quality then probably 64Kbps is the lowest you'd want to use. Theoretically your .wav files and CD files should be exactly identical copies of each other. If you're getting something different back from the CD then either your burning software or your ripping software is doing something it shouldn't oughta be doing. The uniform clipping indicates either a lot of excess compression or a lot of distortion, both of which are undesirable. What software do you use for burning and ripping? Do you add any additional steps, filters, settings, or processing? You shouldn't be. Also, if you're making changes to the WAV files, why wouldn't you use those for creating the MP3 files? Seems like that would be faster and more convenient than ripping the stuff back from the CDs. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 4:55:48 PM
I've been burning the CDs using Nero 7 Essentials. A few years ago already, I came to this forum because the CDs weren't playing well in car players, and was advised to lower my burning speed from 40 or 48 to 8x, and it's worked beautifully since then. I'm not sure what the quality slider is, is that the volume slider for the line-in in Windows? I have that set midrange. I used to have the volume from the recorder feeding into the computer set too high, which caused a lot of the sound to be in the red area, but I've learned to lower that. The reason the wav files sometimes differ from the mp3s is because before committing them to the CD, sometimes I go in and edit the wav file a bit more. The reason I'd been using the CDs instead of the individual wav files -- which would make more sense -- is because the Nero has a feature that normalizes the tracks, and some of my CDs are compilations from different interviews. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 5:18:14 PM
uh-oh. I just did some experimenting and found the quality slider, and it seems all this time I've been saving my mp3 files at the lowest quality, and also the VBR at the lowest setting. What is the advantage of moving them to the medium or fastest setting? |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Chienworks
Date:5/1/2009 6:32:47 PM
Ahhh, it's Nero's normalization that's changing the CD versions. Sound Forge has much better tools built in. You might want to take a peek at Wave Hammer. It's nearly automatic and produces much better results than simple normalization. Personally, if i knew i was going to tweak the WAV files, i'd wait until after that was done before making the MP3 files. The quality sliders should always be set for highest quality. Never use fastest as this is the worst quality. The quality sliders have nothing to do with volume; they are completely separate concepts and controls. There's no relationship between them at all. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/1/2009 6:55:49 PM
Thank you, Chienworks. I'm a historian by hobby originally, and a sound editor by default. The sound quality of the CDs (samples at audiomurphy.com) has been OK, that is, no one has complained, but as I expand the line of audio CDs, I want to get it as right as I can. I'll check out Wave Hammer |
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Subject:RE: preparing sizable mp3 files for download
Reply by: rraud
Date:5/1/2009 11:15:49 PM
Warning: Use Wave Hammer sparingly. WH can and will produce very audible distortion when used to excess. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: aelson
Date:5/2/2009 5:28:19 AM
Thanks for the heads-up. I noticed that the default settings on the wave hammer are pretty low, and when I tried moving them up, one file got noticeably louder, so I canceled it and left the settings where they were. I'll proceed with caution. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Chienworks
Date:5/2/2009 5:47:46 AM
There's nothing wrong with louder. It's distortion that is a problem, not loudness. The idea of Wave Hammer is that it can increase the volume of the quieter parts while gently leaving the louder parts alone, which evens out the volume. When used properly it should make the quieter files sound louder, sometimes substantially. This lets them match the louder files. |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Wally T
Date:5/2/2009 12:01:53 PM
Chienworks, You said you move the quality slider all the way to the right. Have you ever tested the different quality settings? Just curious to see. I did and the "Fastest" setting sounded better to me. Check my recent post and test files here: http://www.sonycreativesoftware.com/forums/ShowMessage.asp?MessageID=650916&Replies=0 I really want to see if its just me or if my copy is somehow screwed up. Thanks. Wally |
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Subject:RE: preparing sizable mp3 files for download
Reply by: Chienworks
Date:5/2/2009 12:13:05 PM
Personally i notice very little difference at all between the settings, but if i listen very carefully i can hear that highest quality is slightly better than medium, and fastest is slightly worse than medium. |