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Don't upload to TAXI over 128kbps!

Posted: Wed Apr 25, 2007 8:26 pm
by dhodgson
Just a little lesson I learned tonight...When you visit the "Submit Music" page on TAXI, it says you can upload MP3's encoded up to 192Kbps. This is a mistake. Sure, it will let you do this, but if you try what actually happens is:1) The server recompresses your file to 128kbps, poorly - with audible artifacts2) This process fails to preserve your ID3V2 MP3 tags, so there go your copyright, contact information and cover pic (if any).However, if you upload at 128Kbps your file will remain byte-identical. So... until this is corrected, don't be tricked! If you go for the quality, your upload will only end up sounding worse off.-djh

Re: Don't upload to TAXI over 128kbps!

Posted: Wed Apr 25, 2007 10:46 pm
by gitarrero
I just checked it ... I couldn't hear any "hard" artifacts in my track, though it was over desktop speakers (so i don't really hear the bass).any other experiences?

Re: Don't upload to TAXI over 128kbps!

Posted: Thu Apr 26, 2007 5:06 pm
by allends
Quote:I just checked it ... I couldn't hear any "hard" artifacts in my track, though it was over desktop speakers (so i don't really hear the bass).any other experiences?I just uploaded a song that I had encoded at 192kps to both Taxi and Broadjam. Now, I've been listening closely to the song for days so my ears are really engaged. The Broadjam rendering of the song is vastly inferior to the results on Taxi which I found quite acceptable. I understand that Taxi would forward my 192kps version to the client, not the brodcast fidelity version, so I'm going to continue to submit at 192kps.-Allen

Re: Don't upload to TAXI over 128kbps!

Posted: Thu Apr 26, 2007 7:03 pm
by dhodgson
Well, this isn't one of those "golden ear" things - you can prove it to yourself. 1) Upload your 192K to TAXI. 2) Then "Save As" your Taxi file when it presents you with a "Play File" link. This returns a ".m3u" text file that contains the hidden link to the real file on TAXI's server, and if you grab that you'll see that your song has been recompressed to a smaller 128Kbps file with the ID3 tags stripped. In my case, (and this was what tipped me off) it was a noticeably artifacty recompression - much worse than if I had simply uploaded at 128Kbps in the first place.So, what I'm saying here - and let me be perfectly clear about this - is that if you're uploading at 192K on the Taxi server, that is NOT what Taxi will be forwarding to your client. If it was, there would be no reason for TAXI to recompress your file because the only reason for doing so is to save space on their file server.Now as far as Broadjam goes, if their recompression is worse still, then I can only say... shame on them.-djh

Re: Don't upload to TAXI over 128kbps!

Posted: Thu Apr 26, 2007 9:59 pm
by andreh

Re: Don't upload to TAXI over 128kbps!

Posted: Thu Apr 26, 2007 10:32 pm
by dhodgson
Thanks for the link. It looks like while this behavior has been noticed before, TAXI has yet to make an official comment about it.Now, while I personally find that going over 160Kbps is a diminishing state of returns in terms of audio improvement, for TAXI purposes it makes sense for artists to always upload at the highest bitrate allowed because (unless you're on dialup) there's no good reason not to. And this, I'm sure, is what many people have been doing.Unless something else is going on that I'm not aware of, it would be best for the Submit page to simply state that "submissions over 128kbps are not supported" rather then mislead people that submissions up to 192kbps are allowed when they're really not.Of course, best of all would be to remove the MP3 upload restrictions completely. File-size issues should be dealt with as a separate issue (i.e., "No files over 10MB!") because recompression alone is not capable of solving that problem.-djh

Re: Don't upload to TAXI over 128kbps!

Posted: Fri Apr 27, 2007 3:56 am
by allends
Quote:Unless something else is going on that I'm not aware of, it would be best for the Submit page to simply state that "submissions over 128kbps are not supported" rather then mislead people that submissions up to 192kbps are allowed when they're really not.I'm not sure if I am reading you correctly. I believe that in the previous thread that our friend andreh referred you to it was concluded that Taxi supports 192kbps for downloads and that streaming was limited to 128kbps. If that is true then I would think that your last thoughts quoted above aren't entirely correct. Could it be that you were only referring to the streaming issue?I'm interested in your ideas, that's why I asking. -Allen

Re: Don't upload to TAXI over 128kbps!

Posted: Fri Apr 27, 2007 12:17 pm
by dhodgson
You've got a perfectly legit question, hence the 'unless there's something going on that I'm not aware of' caveat. I don't think it was actually concluded in the other thread that Taxi streams at 128K while supporting 192K for archival purposes - I believe it was merely speculated. And you know what happens when you assume things...So, unless one of us here is a client, there's no way to really know how this plays out in practice until someone from Taxi steps forward to clear this up. In the meantime, I'm going to assume the worst and stick with uploading at 128Kbps because the other proposal (that TAXI actually maintains separate archival and streaming versions of every > 128Kbps file) seems baroque and unintuitive, hence unlikely.-djh

Re: Don't upload to TAXI over 128kbps!

Posted: Fri Apr 27, 2007 12:26 pm
by mazz
Not knowing a whole bunch about the behind the scenes workings of mp3 streaming, could it be possible to have one file at 192K for transferring to clients and use the same file for streaming but "downsample" it to 128K? There would be no need for storing two versions of the file. I bet software exists for this.If what I theorize is true, maybe that's what TAXI is doing?Mazz

Re: Don't upload to TAXI over 128kbps!

Posted: Fri Apr 27, 2007 12:47 pm
by dhodgson
OK! I've got the beef - somebody from TAXI called me up just now to explain this, and gave me the blessing to pass this info along so here goes:TAXI maintains three copies of your file; the one you submitted, (up to 192kbps allowed for archival purposes) and two downconverted versions - one at 128kbps (for when your Profile settings say 'Stream at High Quality') and one at 40kbps (for when your Profile settings say 'Stream at Low Quality').Although the Taxi person I spoke with is not a Webmaster and doesn't know all the mechanics, it does appear that if your upload is 128Kbps to begin with that TAXI doesn't bother regenerating another 128Kbps version just for streaming purposes - it streams the file you sent, byte-for-byte in High Quality mode. In Low Quality mode, it streams a 40Kbps version generated by TAXI.So, we can all breathe a bit easier here - and hopefully this will be mentioned on the Submit Page at some point. However, it still stands that if one wants to either 1) preserve the MP3 tags in one's file when streaming or 2) stream in high quality as Nature intended without suffering from an unnecessary recompression, the only solution there is to upload at 128kbps.Excelsior! And thanks for everyone's patience.-djh