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Living Room / Re: Mp3 File Format Issue Split From Silly Humor Thread
« Last post by f0dder on February 02, 2013, 11:04 PM »The MPEG Layer-3 wav's operates much faster than .mp3 and don't require special players once installed, it decodes on the fly in windows."Operates much faster", how? Do you mean because you can use the extremely stripped-down sndrec32 to play it rather than starting some bigger/slower media player? Or something else?-Tinman57 (February 02, 2013, 06:24 PM)
I can see it sorta makes sense if you want to have your Windows system sounds mp3 compressed, or for other applications that don't support mp3 (it'll only work for mp3-wave if those applications uses Windows APIs - a fair amount of programs, and especially games, parses the .wav by hand, and only supports raw PCM audio - and possibly even only one hardcoded format).
But you do need the codec installed, then, which not many people have these days - especially since all audio players tend to come with built-in mp3 support these days
If I remember correctly, they also make much smaller files than .mp3's. I only use mp3 format for actual music files.Given the same (constant) bitrate, a WAV with mp3 audio should actually be slightly larger than normal mp3, since the wav container headers are in addition to the mp3 stream headers. If you see a size difference of more than a few handfuls of bytes, you're encoding the wav-mp3s with a lower bitrate than the mp3 you're comparing to.-Tinman57 (February 02, 2013, 06:24 PM)
Those three letters, W-A-V are sometimes magic, but sometimes the two letters M-P and the number 3 are even more magical. And in the case of your compressed wavs, that's the only difference between them and MP3's...the three characters after the dot. There is no magic in the file itself.The file formats are different, though - and while the audio stream itself is the same compression format, being in a .wav container can matter - an application might not support mp3, but if it uses Windows APIs to handle it's .wav files, it should be able to play back pretty much any audio format you have a codec installed for.-Tinman57 (February 02, 2013, 06:24 PM)
Was it made on a stock system with no extra codecs installed, using only software or components that ships with Windows?Tinman says he uses l3enc - I'm not sure whether he uses the original l3enc.exe, or compressed by opening input file and selecting l3enc codec - but at any rate, l3enc was the first mp3 compressor (and probably the first codec as well?), developed by Fraunhofer. It has pretty bad quality compared to today's codecs (it had to cut corners to run at acceptable speed - when I first got l3enc.exe, my system was a 486dx4-100), and unless you're using RADiUMs hacked version you're limited to 128kbps (iirc RADiUM not only hacked the codec to support the higher bitrates, but also optimized the (binary) code making it some 5-10% faster...)-app103 (February 02, 2013, 08:18 PM)
Sounds more like it's just MP3 encoded data within a WAV container, (ie. it has a header of RIFF) - so renaming it to .mp3 won't work because the MP3 header info required by a true MP3 decoder is missing and anything that can only handle valid WAV files won't work because the data will appear corrupt. Hence the need for a codec.You're right that it's mp3 encoded data in a .wav file - as your screenshot also clearly shows-4wd (February 02, 2013, 07:53 PM)
However, you're slightly wrong about the header stuff. The following is off top of my head, so might not be 100% correct, but... here goes:
MP3 files don't have headers in the same sense that most other file formats do - which is normally a header located at the beginning of the file, in a fixed format. MP3 isn't a "container format", it's basically just a bunch of MPEG frames that happen to be in the same file. MPEG was made to support "muxing" (having both audio and video in one stream (or file), which means you need to chop up your video and audio streams to pieces and interleave them, since you can't "seek" in streamed audio... and it would've been problematic for optical media which are very slow at seeks)).
So, MPEG revolves around "frames" which can (theoretically) appear anywhere inside your stream (or file). Since the format need to support streams with many small frames, both for muxing reasons as well as jumping into the middle of a streamed broadcast without waiting too long for a sync frame, the identifier (the "MP3 Sync Word") is very short. And it's not very unique - so it wouldn't be a good idea to scan through a file looking for this signature.
ID3 tags are a bit of a mess, but I'm too fuzzy on the details to say much more about them than that. But without them, since MP3 isn't a container format, you'd have to read through the entire MP3 file in order to know it's playtime... so they're definitely welcome
...anyway, file doesn't want to play here, whether I keep the file extension as .wav or change to .mp3 - tried Windows Media Player, mpc-hc or foobar2000. Win7-x64 without any codec packs installed - I might even have removed some, since I tweaked the install a lot (I did keep WMP, though). No go, even if I trash the wav headers.
