FLAC to Apple Lossless SLOW

[oehlrich]

Hello,
yesterday I downloaded dBPoweramp to convert some of my FLACs to Apple Lossless for my iPodTouch. I hoped from lossless to lossless format this is quite a quick task so I can pump up my iPod right before I enter my car.

Testing this I got quite different results. Having FLAC files without metatags inside conversion is 12x speed. But as soon als metatags are inside the conversion hangs a long time with "Writing ID Tags 'Track title' which slows down the whole process to 0.9x - 1.0x speed. During this hanging nothing happens on the harddisk but CPU-usage is 100%

With this performance dBPoweramp ist much too slow for what I need.

Any idea?

Charly

[Tigerman]

Re: FLAC to Apple Lossless SLOW

Don't use apple lossless normally, but I converted an album with tags and it reached an encoding speed of 88-94 times (AMD Dual Core 6000+).

So there must be something wrong with your install. Try uninstalling and reinstalling the m4a codec.

[Spoon]

Re: FLAC to Apple Lossless SLOW

Convert to your Main HDD, not a network or USB HDD (such as the IPod), then copy after.

[oehlrich]

Re: FLAC to Apple Lossless SLOW

Well,
I investigated a bit the conversion Process from FLAC to AppleLossless and found out:

- Converting without any tags I get 13x conversion speed
- Converting with Artist, Title, Track and Tracknumber tags also 13x speed
- Converting with the above PLUS a 300x300pix JPEG coverart I goes down to get 1x speed while writing the tags

What now?

Seems to be an issue in cover art conversion. I someone is interested I can submit a FLAC that converts extremely slow.

Charly

[Spoon]

Re: FLAC to Apple Lossless SLOW

If you are converting to a USB or Network drive then yes potentially it can be slow (as there is no caching).

[oehlrich]

Re: FLAC to Apple Lossless SLOW

Spoon,
it is not an issue of the drive. I did more research and the result got more and more funny but reproduceable.

I rip a CD with Ripstation Micro DS to FLAC and add the cover with Mp3tag (it handles FLAC). Playing this with foobar anything works great. Converting THIS file to AppleLossless it is very slow.

What I did now:
I inserted all these files into Mp3Tag and delted ALL tags. Conversion was fast after that procedure.
I add Artist, Title, Track and Tracknumer AND the image with Mp3tag. The conversion STAYS fast!

After that procedure I have two FLACs with same Tag content. One file converts fast the other one slow.

Interested in both files?

Charly

[oehlrich]

Re: FLAC to Apple Lossless SLOW

Spoon you can download both files here:

http://freerider.dyndns.org/definiteAudio/kunden/dBpoweramp/01_Fast.flac

http://freerider.dyndns.org/definiteAudio/kunden/dBpoweramp/01_Slow.flac

They are on my private server and this is low speed DSL so be patient (30.275kb each).

Charly

[Spoon]

Re: FLAC to Apple Lossless SLOW

Take slow.flac and convert to Apple Lossless starts out a x40, if Verify Apple Lossless is on then drops to x9. If verify is not on then drops to x11 - this is to be expected as m4a have the ID tags at the front of the file and tagging the file requires the whole file to be re-written.

[oehlrich]

Re: FLAC to Apple Lossless SLOW

Spoon,
on my machine (Via C7 1,2GHz) it starts with 13x and goes down to 1x. This ONLY with the slow.flac. The fast.flac has the same tags. It also starts at 13x bou dropts to 11x.

Have you an explanation where the difference between the two files comes from?

Thanks Charly

B.T.W. Ripping with the dBPoweramp Ripper the created FLACS are like my fast.flac and speed is not decreased.

[Spoon]

Re: FLAC to Apple Lossless SLOW

if one has album art and the other does not then the moving of the whole file to accommodate the album are is likely the cause. FLAC even though having ID Tags at the front of the file, allows for padding.

[someGuru]

Re: FLAC to Apple Lossless SLOW

AV on access scanning of the folder.jpg due to the hidden and system attributes will greatly reduce thoroughput, x2 when converting and tagging.