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Topic: Help from LAME developers/insiders needed (Read 4148 times) previous topic - next topic
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Help from LAME developers/insiders needed

Yesterday I bought for my kids portable CD/MP3 player from Roadstar (PCD-3048MP). As it was very cheap indeed (just funny 65 Euro pro piece) I took right away two... From tech specs I found out that this device is capable of playing up to 384 kbps. Well, I tried it and it really works. Now I would be very thankful for any commandline to get the best possible results for such a high bitrate.

Help from LAME developers/insiders needed

Reply #1 –
--alt-preset insane

afaik any freefromat setting would not be even remotely as well tuned as api
A riddle is a short sword attached to the next 2000 years.

Help from LAME developers/insiders needed

Reply #2 –
I'd say use --alt-preset insane, because it's tested and its few weaknesses are well known. If you insist on wasting bits  : --freeformat and VBR don't like each other - so what about trying --alt-preset insane --freeformat -b 384. I can't tell if this will do any harm. Seems like you have to find out yourself.

FYI: About your cheap portable player: I have a similar one too (and a mate of me has a roadstar car mp3-CD player). Both have no mp3 problems (bitrate/vbr ... ) but seem to have DAC problems that cause aliassing/distortion on signals >16kHz. I recommend you record some test signals (e.g. sine sweeps) on CD-R (maybe also as mp3s) and check this. Maybe you need some kind of lowpass or -Y (if you use VBR) to improve this.
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Help from LAME developers/insiders needed

Reply #3 –
tigre:

In fact I tried --alt-preset insane --freeformat -b 384 -m s but some artifacts appeared now and then in the right channel (w00t) as somebody was tapping on my headphones from the outside... It was very strange. The -m s parameter I inserted just after experiencing this artifact, but it stayed there without any change 
As for the high freqs, I have 6 CDs (Coldplay, Pulp, Smashing Pumpkins, Mick Jagger, Manic Street Preachers, Gorillaz, Puddle Of Mud, Down, Sum41, Green Day and alike stuff) full with MP3s (--alt-preset insane --lowpass 21) and by random testing I experienced no problem; the same goes to VBR (ape).

Help from LAME developers/insiders needed

Reply #4 –
Quote
but some artifacts appeared now and then in the right channel (w00t) as somebody was tapping on my headphones from the outside...

maybe the hardware players' decoder is somehow buggy, it could have problems with bit reservoir ore something like this. You could try to decode with MAD and find out if the artifacts are audible in the decoded .wavs too.
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Help from LAME developers/insiders needed

Reply #5 –
At > 320kbps, its not really the lack of bits per second which lets the MP3 format down -- so you aren't going to improve by going above that...

My DVD Player will go up to 384kbps as well, even on (S)VCD Encoded films -- doesnt sound any better though (than 224kbps, to be honest)

Help from LAME developers/insiders needed

Reply #6 –
budgie:  maybe you have some clipping ?  try scaling when encoding with LAME

Lev:  I agree..  some samples are problematic up to 384kbps CBR, but trouble disappears if one uses --alt-preset insane.  This shows how well tuned Dibrom's command lines are 

Help from LAME developers/insiders needed

Reply #7 –
NumLOCK:

To be honest, I really do not know... It's Midnight Oil's "Capricornia" track...

Help from LAME developers/insiders needed

Reply #8 –
Quote
NumLOCK:

To be honest, I really do not know... It's Midnight Oil's "Capricornia" track...

Just in case you don't know: To find out if it's clipping use MP3Gain (and get rid of clipping caused by encoding at the same time).

MP3Gain guide from HA FAQ

If you you use mp3 on hardware players and care about quality you want to use MP3Gain for sure.
Let's suppose that rain washes out a picnic. Who is feeling negative? The rain? Or YOU? What's causing the negative feeling? The rain or your reaction? - Anthony De Mello

Help from LAME developers/insiders needed

Reply #9 –
384kbps is the maximum bitrate for layer 2 (mp2), whereas 320 is the maximum bitrate for layer 3 (mp3). Compliant decoders are required to support these, but they are not required to support mp3 freeformat - very few do.

The reason for the misleading specs on your player is probably because a compliant mp3 decoder should also play mp2 and mp1. So, the maximum bitrate stated for your "mp3" decoder is probably 384kbps for playing mp2 files.


If it works with freeformat mp3 at 384kbps, good luck to you!

But
a) the problems you're hearing are probably because it's freeformat - the decoder can't really cope properly, and
B) lame behaves very differently using high bitrate freeformat modes, so hacking the alt-presets to work up there is not likely to give the quality you desire.

I'm not saying (B) from any knowledge of the source code. It's from looking at a spectral analysis of the output minus the input. This is not a good way to judge the quality of a psychocaoustic codec, but it's revealing of the underlying process in this specific case: What comes out at, say, 640kbps is very strange - the coding noise is not psychoacoustically shaped - it's broad band - and (obviously at 640kbps) very quiet.

http://mp3decoders.mp3-tech.org/freeformat.html

Cheers,
David.

Help from LAME developers/insiders needed

Reply #10 –
2Bdecided:

First I thought it was an error in "manual" (range of this device is 32-384 kbps), but then it really worked with LAME... but now I try to encode it as .mp2 and play it. I like the sound of mp2 much, so I just give it a try.
 

Help from LAME developers/insiders needed

Reply #11 –
Well, after thorough test I can confirm that this device plays 384 kbps CBR MP2 with .mp2 suffix; MP2 renamed to MP3 and thru MP2ENC encoded MP2 with .mp3 suffix. I simply love this Roadster... 
The artifacts in LAME freeformat 384 kbps persist, but it's no problem anymore after this MP2 issue.