Support and General Use > Audio Playback, Database and Playlists

lame mp3's not completely gapless on 5G ipod

<< < (4/9) > >>

saratoga:

--- Quote from: michael.conner on September 10, 2006, 04:34:20 PM ---The best way to get gapless playback w/Lame-encoded MP3's is to use the "--nogaptags --nogap" command-line switches using the .EXE file.
--- End quote ---

This is actually a terrible idea.  --nogap is an ancient hack thats totally unneeded in rockbox.  LAME has been completely gapless without it for about 5 years now.  Its only useful for crappy decoders that can't handle gapless playback correctly (and even then it rarely works).

michael.conner:

--- Quote from: saratoga on September 10, 2006, 05:31:24 PM ---
--- Quote from: michael.conner on September 10, 2006, 04:34:20 PM ---The best way to get gapless playback w/Lame-encoded MP3's is to use the "--nogaptags --nogap" command-line switches using the .EXE file.
--- End quote ---

This is actually a terrible idea.  --nogap is an ancient hack thats totally unneeded in rockbox.  LAME has been completely gapless without it for about 5 years now.  Its only useful for crappy decoders that can't handle gapless playback correctly (and even then it rarely works).


--- End quote ---

I stand corrected -- and totally surprised!  Thanks for the info.

Old habits die hard -- I used to have an Archos JBR, so I've been encoding live CD's and other albums that would need gapless playback that way for years now.  

Llorean:
The one *advantage* of the --nogap option is that the whole CD is encoded in one go, and then split, I believe, which means the gap will be 100% seamless even in those problem cases where the current gapless in LAME will sometimes have a very slight audible difference in the sound, even though there's no actual *gap*. At least, that's my understanding.

Of course the _huge_ disadvantage is that you're cutting at frame boundaries so that in many cases you actually get a little of the prior track in the current one (or a little of the next track in the current one, I don't know which way it cuts)

saratoga:

--- Quote from: Llorean on September 10, 2006, 06:03:47 PM ---The one *advantage* of the --nogap option is that the whole CD is encoded in one go, and then split, I believe, which means the gap will be 100% seamless even in those problem cases where the current gapless in LAME will sometimes have a very slight audible difference in the sound, even though there's no actual *gap*. At least, that's my understanding.

--- End quote ---

I believe the output should be the same on a gapless decoder like rockbox with and without nogap (well when comparing the entire CD, obviously the tracks won't be the same length as you mentioned).  Its literally just creating one giant MP3 like with a cue sheet, and then splitting it up at the end.  The splitting process should be lossless, though the MP3s probably won't be identical anyway because the bit resivior will be packed different due to the different track lengths.

There also shouldn't be problem cases with LAME, just broken files and broken codecs. As far as I'm aware, the current lame.exe and a compliant decoder like foobar2000 can produce sample accurate decoded mp3s for all possible source files.  If you're not getting sample accurate output, theres probably something wrong with your lame compile (as in this thread) or you have a broken tag.

The problem with nogap is that it assumes that your decoder can output two MP3s back to back without inserting a single sample of silence.  Very few decoders can do this aside from those designed to be gapless with LAME anyway.

preglow:

--- Quote from: saratoga on September 10, 2006, 09:33:25 PM ---I believe the output should be the same on a gapless decoder like rockbox with and without nogap (well when comparing the entire CD, obviously the tracks won't be the same length as you mentioned).  Its literally just creating one giant MP3 like with a cue sheet, and then splitting it up at the end.  The splitting process should be lossless, though the MP3s probably won't be identical anyway because the bit resivior will be packed different due to the different track lengths.

--- End quote ---
I think there's a slightly greater chance of an audible glitch at the track transition if you don't use --nogap. You'll seldom hear it in normal use, but I've provoked a very audible glitch doing some very synthetic tests. No gap or anything, just a glitch thanks to how MP3 works internally.

Navigation

[0] Message Index

[#] Next page

[*] Previous page