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Topic: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround (Read 15828 times) previous topic - next topic
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batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

TL;DR looking for advice re re-encoding existing 320k CBR mp3 files >> new fresh 320k CBR mp3 files, made with lame 3.100
I'm using linux, and looking for best parameters to minimise losses.

Use case is specifically to play mp3s from USB stick in a car of which the software / audio system cannot be changed. 

Background:
My car has an audio system which is quite fussy about file formats. Filenames and meta data with special characters caused it to flip out and a few other random issues.   Can't do anything about the car and its software (let's not go there).
Such files would always play on a PC and phone, but refuse to play from USB stick. So diagnosis is hard.
So I though I had it locked down and problem gone.  Then earlier this year problems started again.

It's not conclusive, but these problems seemed to be related to 3.99.  Did the same removing of special characters, removing comments and art, but no luck.    Same files created with 3.93 play just fine in the car, so do files made with 3.100.  Not a problem for files I make myself from CD or FLAC. But...

Recently I've received files made by a windows software, where they seem to have coded in LAME 3.99 and not the latest version.  They refuse to play in the car. I've re-encoded a few using audacity as an experiment, and sure enough 3.100 works fine.

So now I'm going to make a script to try and get these files in 3.100 by batch process.  Any help greatly appreciated.


;)  ;)  For the inevitable "just stream from your phone" answers, yes I do that as well, but I want USB to work too.

 

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #1 –
* Have you checked what version(s) of ID3 tags the files use? Or some have Lyrics extension or APE tags? "Easy" test: make a copy of a folder with troublemakers, use some utility that removes all tagging. (I mean all! Some players would only read & write (& erase) one particular tag format.) See if it makes a difference.

* You can try the following alternatives to re-encoding:
1: ffmpeg re-encapsulation. With -acodec copy. It takes the stream and puts it in another mp3 file.
2: http://wiki.hydrogenaud.io/index.php?title=MP3packer . (MP3 works by first a lossy element, and then a packing element that is just as lossless as zipping.) IIRC this creates "less fancy" header fields (you might lose gaplessness and such) - and if those fields are what are troublesome, you might want this. Also, if your car player chokes on bitrate - which I think has been an issue with certain players in the past - it might prefer a better-packed 310 over your 320.  (OTOH, it might not like VBR at all?)

* Transcoding is generally suboptimal, so you should keep your original files - but there is no way you will need CBR320 in a car (you could divide by four!), so you might just as well make lower-bitrate files than that. If bitrate is the problem, it will get resolved at the same time.
(When I have to transcode lossies, I just give them a special name ... How many files of yours have the ¨ character? It is pretty uncommon, but I have yet to see it make any issue.)

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #2 –
Quote
looking for best parameters to minimise losses.
If you have to re-code, the default settings at 320kbps are probably the best you can do.   Re-encoding is "lossy", even at the same, or higher, bitrate but at 320kbps you may not notice any difference, and of course it's better in your car if you can play it. ;)

You might try MP3 Diags.   It might tell you what's wrong with your MP3s and it may be able to fix them.   (I'm a Windows guy, but there is a Linux version.)

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #3 –
Try MP3packer maybe it will make your files playable losslessly.

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #4 –
Or try foobar200, which has a "rebuild mp3 stream" utility built in

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #5 –
Many thanks guys - lots of things for me to check out. 

Quote from: Porcus on
....there is no way you will need CBR320 in a car (you could divide by four!), so you might just as well make lower-bitrate files than that.
That's true in a lot of scenarios.  On this one, you can tell the difference between a CD and a 320k file, but it's acceptable. A 192k file sounds garbage.     I know that cars often mask this, but it's a factory audio engineered Bowers and Wilkins option with 17 speakers.  With a recording of a mouse farting, you can tell what colour seeds it had for dinner. ;) ;)

It could all be in my head, but I'm truly grateful for the help :)   It'll take some time for me to try them all but I'll report back with what I find out.

Re: batch re-encode mp3 made with lame 3.99, to lame 3.100 - Car Audio workaround

Reply #7 –
 :o   My apologies.  That's actually a great rule to have, please forgive my noobness.