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Topic: Converting Flac8 to Flac2 (Read 7068 times) previous topic - next topic
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Converting Flac8 to Flac2

Hi,

I have about 50 gig of flac level 8 files on my hard drive which I need to convert to flac level 2. I'm guessing I need to go from FLAC 8 > WAV > FLAC 2. Is there a way I can do this all at once or at least FLAC 8 > WAV then WAV > FLAC 2, instead of folder by folder (some kind of batch file perhaps). 

Please bear in mind that I'm pretty new to FLAC and know absolutely nothing about batch files.

The reason I need to do this is that I've just bought an Iaudio M3 which only supports FLAC up to level 2.

Any help would be greatly appreciated

Thanks

Dugq

Converting Flac8 to Flac2

Reply #2 –
Officially the M3 supports FLAC up to level 3 AFAIK (check the iaudiophile.net M3 FAQ), but it may very well be the case that your level 8 files can also be played correctly (as long as you don't use (a lot) DSP's).

Converting Flac8 to Flac2

Reply #3 –
If you ripped your Flac 8's to a single image and a cue, foobar will also convert multiple file flac's if you wish or the other way round if you want no gaps (i assume the iaudio M3 is not gapless playback)

another consideration when playing flac's is battery drain, you might want to test how it compares to mp3 before converting all 50 flac's

Converting Flac8 to Flac2

Reply #4 –
Thanks all,

The M3 hasn't been delivered yet, so I'll wait until I get it and then try the Level 8 flacs and see if it can cope, I not a believer in DSP effects anyway.

If it can't do it then I will probaly use Foobar, I've been using it for a while now although I've only scratched the surface of what it can do. I just experimented using Foobar to create a level 2 single file out of seperate flacs, and it seems to be okay (M3 isn't gapless)

One question though, when Foobar converts to flac, does it verify the files like flacfrontend does. I can't seem to find the specific setting in Foobar

Thanks

Dugq

Converting Flac8 to Flac2

Reply #6 –
Quote
One question though, when Foobar converts to flac, does it verify the files like flacfrontend does. I can't seem to find the specific setting in Foobar
[a href="index.php?act=findpost&pid=288030"][{POST_SNAPBACK}][/a]

Foo_flaccer always uses verify.

Converting Flac8 to Flac2

Reply #7 –
Thanks. 

I think thats all the questions I have for now, although I imagine once I get the M3 I'm going to have a few more questions

Cheers

Dugq

Converting Flac8 to Flac2

Reply #8 –
Why would a device only support FLAC up to 2?  That seems useless.  Doesn't flac actually decode *faster* when using 8?  That almost seems useless that it wouldn't even support the default FLAC mode.

Converting Flac8 to Flac2

Reply #9 –
I believe the higher the #, the more compressed it is. The audio player may lack the processing power needed to decode them.

Converting Flac8 to Flac2

Reply #10 –
Quote
Why would a device only support FLAC up to 2?  That seems useless.  Doesn't flac actually decode *faster* when using 8?  That almost seems useless that it wouldn't even support the default FLAC mode.
[a href="index.php?act=findpost&pid=288106"][{POST_SNAPBACK}][/a]
FLAC <=2 uses only the fixed polynomial predictors, which can be decoded using addition only.  FLAC >=3 may (and mostly does) use LPC predictors, which require multiplication to decode.  I'm not familiar with the hardware in the M3, but fast multipliers are very expensive in terms of chip real estate and thus a reasonable thing to omit from an embedded processor.

--John

Converting Flac8 to Flac2

Reply #11 –
you can pipe flac decode to flac encode:
flac -d cymbals.flac -o - | flac -2 - -o cymbals2.flac


later

Converting Flac8 to Flac2

Reply #12 –
Quote
FLAC <=2 uses only the fixed polynomial predictors, which can be decoded using addition only.  FLAC >=3 may (and mostly does) use LPC predictors, which require multiplication to decode.  I'm not familiar with the hardware in the M3, but fast multipliers are very expensive in terms of chip real estate and thus a reasonable thing to omit from an embedded processor.


Ah... this is news to me.  I didn't know that flac was engineered like that.  Whenever I had seen tests done, the decode speed was almost similar, and often faster at the higher compression levels, but I guess this woul explain why that would be the case on a PC, and not on some hardware players.  It's just a matter of the hardware architecture.

Converting Flac8 to Flac2

Reply #13 –
Quote
Why would a device only support FLAC up to 2?  That seems useless.  Doesn't flac actually decode *faster* when using 8?  That almost seems useless that it wouldn't even support the default FLAC mode.
[{POST_SNAPBACK}][/a]
Any regular FLAC encoding level (i.e. not --super-secret-etc.) decodes at about the same speed, with only very nominal speed degradation going up encoding levels. Have a look at [a href="http://people.ucsc.edu/~rswilson/flactest]Omion's test[/url] for more in-depth info.

Converting Flac8 to Flac2

Reply #14 –
Ah, it does appear (from that test) to decode faster at lower settings.  I did see results someone had posted that seemed to indicate that with their particular file, flac8 decoded faster, but it probably wasn't a very accurate test.

Still, the differences in decoding speed are marginal, which is one of the great things about FLAC.  That *does* seem rather unfortunate that hardware playback ability could be compromised by the higher settings.  Especially for those of us with extremely fast PCs, and very slow DAPs with FLAC playback.

Converting Flac8 to Flac2

Reply #15 –
Quote
Ah, it does appear (from that test) to decode faster at lower settings.  (...)
Still, the differences in decoding speed are marginal
Indeed.  Omion's tests mention 69-70x real-time decoding speed for encoding levels 4 to 8, vs. some 72-73x for level 1 to 3.
A negligible difference, if you ask me, especially if you look at the full-scale graph.

Converting Flac8 to Flac2

Reply #16 –
Quote
Still, the differences in decoding speed are marginal, which is one of the great things about FLAC.  That *does* seem rather unfortunate that hardware playback ability could be compromised by the higher settings.  Especially for those of us with extremely fast PCs, and very slow DAPs with FLAC playback.

the difference is still minor.  the M3 officially supports only the lower compression levels but we've had feedback on the FLAC lists that FLAC -8 plays fine.  maybe it's right on the edge, I don't have a device to test with, but if it is, all it will take is asm optimization of a single simple function to solve that.

Josh

Converting Flac8 to Flac2

Reply #17 –
Cool!  Have been able to convince your loyal followers to mail you all kinds of DAPS for free yet?  I suppose the only one that does you much good is the neuros, in terms of actually being able to contribute personally to the development of the firmware.

By ASM optimization, did you mean in the firmware, or in your FLAC encoder?

Converting Flac8 to Flac2

Reply #18 –
Quote
Cool!  Have been able to convince your loyal followers to mail you all kinds of DAPS for free yet?  I suppose the only one that does you much good is the neuros, in terms of actually being able to contribute personally to the development of the firmware.

no, the only manufacturer that has donated anything was slimdevices; I am in the middle of testing the squeezebox2 and will do a writeup on the flac site when it's done.

I don't really ask for hardware and I can see how it might not occur to mfrs to do this but it does help get things going because I have more to do than time allows.  when a box just shows up that saves me a lot of hassle!

it's unfortunate though because I would like to have more first-hand experience with devices, to put on the FLAC site.

Quote
By ASM optimization, did you mean in the firmware, or in your FLAC encoder?

actually, I think cowon is using libFLAC in the M3, so if someone (me or them) wrote an arm version of one decoder function, that would do it.  I have talked to their engineers about that.

Josh