How Do I prevent that dMc increases the bitrate?

[Chefi]

Hello and a first sorry for my bad english.
I´m using dBPoweramp for convertig my existing library for multiples devices (Mobile Phone, Car Radio etc.).
The most ones are mp3,wma,m4v (around 168-320 kbs). some flac and even a few very low bitrate mp3 (about 100 pieces at 64kbps)
For the Radio of our Car I want to convert the songs (around 1700) to Lame Mp3 -v2. It works very fine for the good qualitiy titles, they become smaller, but it increases the 64kbps ( these are "radioplays" (google translation for German "Hörspiele", im not sure if it means the same), so 64 kbps is enough, but they are pretty long) to such big file sizes that i won´t get the whole collection to our 16 GB Radio (same for 168kbs mp3 as well, but that is not the maine point, as well its the same problem and would also stop in the same step).
So How do I prevent the Converter (best tool avaiileble in cases of qualitiy and speed) from increasing the bitrate?
It also generates a crackle-sound which wasn´t there as a 64kbps-mp3. My little brain imagines a working little-dMc-men putting useless rubbish into the mp3-container to make his master(me in this case) happy by complying with the -v2 bitrate.
It would be very important to keep the posibility of converting all music at once because of a very fast growing collection of devices and titles (2 musician parents, 3 children at each age).
Hoping you can help me,
Chefi

Edit: I wrote dMC, but for the hole library consisting of many folder I use of course the batch converter.

[Spoon]

Re: How Do I prevent that dMc increases the bitrate?

When converting lossy to lossy, it is not a great assumption to make that 128kbps of one format (such as WMA) should be 128kbps of mp3, because the encoders are very much different, and the loss of audio by the wma encode followed by more loss (mp3 encode) will only compound it.

[Porcus]

Re: How Do I prevent that dMc increases the bitrate?

Chefi:

1) LAME's -v[something] switches are for variable bit rate. Then LAME targets a certain quality level; it will increase bit rate if it finds something it thinks need it, and reduce it when it thinks it can get the same quality for cheap. It works well on encoding music from lossless sources. Likely less good on speech.

2) What you should avoid unless you have to do, is transcode lossy to lossy. That is a generation loss; if you transcode from 48 kb/s to 128 kb/s, the artifacts become worse despite the size going up - and that's what you have experienced.

Suggestion: keep your 64 kb/s Hörspiele in a separate folder on your hard drive, and don't transcode them - instead, just copy them.

[Chefi]

Re: How Do I prevent that dMc increases the bitrate?

Hey, thanks for your first answers and sorry for my late answer, our hole village was without internet for the last 5 days.
I´m doing music converting for a long time, and i wrote that the newest titles are in flac. Some are at "pretty good" lossy formats, and for our Stereo at home we use only the best availeble formats our library has. But for a huge amount of mobile devices (Car-Radio, IPhone) this would be a nice option. Ok, for the Hörspiele i could do this, but there are many 128kbs wma for example, and it would be great to convert it (when i use the same bitrate lame does not add any artifacts hearable at lower end hardware, IMO) to mp3 to make it availeble for our car.
So doesn´t Lame or DMC have this option? In this case i would have to order my music after bitrate, for example in 20-kb/s, which would be a lot of work.