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Transcoding entire lossless archive to m4a, What are the downsides?
FulciLives
post Dec 2 2009, 05:05
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QUOTE (RendoR @ Nov 10 2009, 17:36) *
I seem to be having issues with ALAC encoded with DB Poweramp. Every track fails the Foobar Foo_Verifier test, it says the track lengths are a mismatch. The newest Foo_Verifier will check Accurate rips data base. DB Poweramp encoded ALAC albums all come up "not a proper gapless album". Also when I do a Bit Compare test against the Flac files that were transcoded, they all come back bad! BTW, I'm using the Ref 13.3 version of DB with all the latest plug ins.

Conversely, when I use Cue Tools with the latest ffmpeg ALAC encoder, every track passes the Foo_Verifier test, the Bit Compare, and the Accurate Rip (within Foobar). Everyone keeps telling me that FFmpeg is NOT archive ready. I beg to differ. Even if 1/1000 tracks is bad, the other 999 pass Foobars tests where DB fails every time. itunes encoded ALAC pass all those Foobar tests too. I see no reason not to use ffmpeg with Cue Tools. I like it better anyway because it creates an accurate rip log and it copies over the EAC log to the new folder. It makes a cue sheet with .m4a extensions but they can always be edited to work with .wav down the road.

I would like to know why DB Poweramps ALAC encoder has so many problems with Foobar though.

Very interesting. I've always used "Easy CD-DA Extractor" when doing FLAC to ALAC and now I wonder how it is working ???

I have an iPod Touch 2nd Gen hence the need for Apple Lossless otherwise I would leave everything in FLAC (and so far I have which means double the HDD space on some things as I keep them in FLAC and ALAC)

I love the iPod Touch but man I wish it just played FLAC crying.gif
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spoon
post Dec 2 2009, 10:00
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>why DB Poweramps ALAC encoder has so many problems with Foobar though.

Rip a CD to both ALAC and wave, then convert a ALAC file to Wave with dBpoweramp, then bit compare the audio stream - they should be identical, or you can switch on the verify option when encoding ALAC (which does the same thing, after encoding it is decoded and compared with the source data). If you are not using the latest beta release of the ALAC encoder (forum.dbpoweramp.com >> Beta >> m4a & Apple Lossless) then it is a good idea to do so.


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jcoalson
post Dec 2 2009, 20:16
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QUOTE (FulciLives @ Dec 1 2009, 23:05) *
I love the iPod Touch but man I wish it just played FLAC crying.gif

make sure to ask
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MrSinatra
post Apr 23 2013, 12:02
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ok, I have some really stupid questions here:

first, how does flac store gapless playback info?
second, if I convert flac to alac, will the gapless info make it into the pgap atom? and will it be "proper"?
third, if I rip direct to alac using this guide:

http://wiki.hydrogenaudio.org/index.php?title=EAC_and_ALAC

will the resulting files have the proper pgap info in them?

thx!
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lvqcl
post Apr 23 2013, 12:17
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Usually lossless formats don't need extra metadata to be gapless
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probedb
post Apr 23 2013, 14:00
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QUOTE (MrSinatra @ Apr 23 2013, 12:02) *
ok, I have some really stupid questions here:

first, how does flac store gapless playback info?
second, if I convert flac to alac, will the gapless info make it into the pgap atom? and will it be "proper"?
third, if I rip direct to alac using this guide:

http://wiki.hydrogenaudio.org/index.php?title=EAC_and_ALAC

will the resulting files have the proper pgap info in them?

thx!


You'll get more responses if you create a new topic about your own question instead of reopening an ancient mostly unrelated topic.
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DonP
post Apr 23 2013, 16:43
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I don't know if any are compatible with ipod, but some music programs will transcode from flac to lossy on the fly as they load files onto a DAP. Then you only need to maintain one format.
Edit: sorry... didn't see this was already covered.

This post has been edited by DonP: Apr 23 2013, 16:51
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db1989
post Apr 23 2013, 17:13
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As lvqcl implied, a lossless format must be gapless by definition. A competent encoder will include all of the input data, just as a competent decoder will decode it in its entirety. If the end-user had to worry about ensuring these processes worked properly, it wouldn’t be a very good format.

IOW, I don’t think you need to worry.

This post has been edited by db1989: Apr 23 2013, 17:15
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MrSinatra
post Apr 23 2013, 18:24
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thx for the replies.

yeah, it looks like flac is natively gapless, no extra info.

one would think ALAC is too, b/c it is also lossless. but my concern is the m4a/mp4 container its in. that has a tag "atom" of "pgap" for storing gapless info, but perhaps that only matters when the container is used with a lossy codec?

I was just asking in case anyone knew for sure?
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skamp
post Apr 23 2013, 18:35
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I'm unaware of a "pgap" field. What software is able to display it? I tried neroAacTag and foobar2000.

Gapless info is written by the encoder. Lossless codecs don't need it, and both Nero AAC and qaac write an "itunsmpb" metadata field that allows for gapless playback on every software that supports it.


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MrSinatra
post Apr 29 2013, 12:47
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yes, all lossless SHOULD be gapless. but ALAC is typically in a m4a / mp4 container, which has a pgap atom. this may only apply to lossy m4a, but that's the heart of my question.

http://atomicparsley.sourceforge.net/mpeg-4files.html

http://code.google.com/p/mp4v2/wiki/iTunesMetadata
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db1989
post Apr 29 2013, 12:50
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So? Said container can store various things. My presumption is that said atom is specifically for lossy files. This is based on the fact that, as described above, a lossless format should not require any special help to be gapless as that should be an inevitable feature of the compression.
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greynol
post Apr 29 2013, 12:59
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Is it really necessary to necro-bump this discussion in order to ease a fear that is completely off-topic?

This post has been edited by greynol: Apr 29 2013, 17:27


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