Maconnect

[Fabio]

well I burned an audio disc with a 0sec pregap and ripped it back on windows. Everything was fine. The CD also plays perfectly fine with media player. I don't know what's going on, maybe an os x related bug ? I don't know

[Fabio]

Do you think the audio glitch is only between the first and 2nd track or do you hear it between every track ?

[djmastera2000]

between every track

[Fabio]

Do you hear the glitch on a desktop/car/hifi set CD player ? Or just when playing it on the mac ?

[djmastera2000]

Sorry, was not at home.

It is noticable on every player (PC, HiFi, Car, etc.)

[edgar]

I can confirm this bug, when burning a cue+mp3 as a continuous mix. I played the cd in a car and there were noticable skips between tracks.

[Fabio]

I just have no idea why there is that glitch between the tracks. I've tried burning two sine waves (440Hz and 880Hz) and rip the burned CD and clearly the ripped tracks are not what they should be. But I don't know why.

[djmastera2000]

Hm, no more ideas?

PS: Happy New Jear!

[edgar]

Happy new year all!

I suspect that the last 2 seconds of every track is missing. When I compare the burnt CD to playing the cue&mp3 in Vox/VLC, the beginning of tracks are right but they all end too soon. Not sure if it exactly is 2 seconds ...

[Fabio]

Ok I'll post detailed results in 2-3 days. If I don't, remind me.

[edgar]

It took some time to puzzle out. I ripped a CD, converted to mp3 & cue and written the it again to a virtual device using Virtual CD/RW (shareware unfortunately). Then used bchunk to convert the generated bin/cue to separate WAV files so I could use a tool to measure track lengths.

Ok, here's the CUE for the first 5 tracks (and the 6th):


TRACK 01 AUDIO
TITLE "Track01"
PERFORMER "Unknown Artist"
INDEX 01 00:00:00
TRACK 02 AUDIO
TITLE "Track02"
PERFORMER "Unknown Artist"
INDEX 00 00:07:25
INDEX 01 00:07:27
TRACK 03 AUDIO
TITLE "Track03"
PERFORMER "Unknown Artist"
INDEX 00 01:45:05
INDEX 01 01:45:10
TRACK 04 AUDIO
TITLE "Track04"
PERFORMER "Unknown Artist"
INDEX 00 02:00:34
INDEX 01 02:00:35
TRACK 05 AUDIO
TITLE "Track05"
PERFORMER "Unknown Artist"
INDEX 01 03:27:60
TRACK 06 AUDIO
TITLE "Track06"
PERFORMER "Unknown Artist"
INDEX 00 03:43:61
INDEX 01 03:43:63

Seems a bit like a mess to me with micro gaps. Some tracks have only index 00 while others have index 00 and 01. Ohwell, the original seems to play fine.

In Audacity, opening the first 3 tracks, this results in the following:

Track 1 starts fine, but ends at 00:07:0266
Track 2 ends at 01:44:0533
Track 3 ends at 01:59:0799
Track 4 ends at 03:26:1066
Track 5 ends at 03:42:1333

Now, if I'm not mistaken that is, the CUE sheet shows frames after the seconds and an audio CD uses 75 frames per second.
So, the actual lengths would be:

Track 1 = 00:07:02
Track 2 = 01:37:02
Track 3 = 00:15:02
Track 4 = 01:27:02
Track 5 = 00:16:02

Trying to figure out a pattern, it would be round down to the nearest second and then adding 2 frames?

[Fabio]

Awesome, thank you.

[Fabio]

Allright this is what I have so far.

Disc 1

Track 1 : 440Hz sine 1500 frames, 2s pregap
Track 2 : 880Hz sine 1500 frames, 0s pregap

Burned using Toast
Extracted with dd and The Finder and analyzed with Audacity

dd: sizes = both 1500 frames
finder + audacity: track 1 has prepended blank audio, but only 1.13 frames instead of the expected 150 frames (2s pregap)
track 2 has ~2 frames blank audio + ~2 frames 440Hz audio, the rest is the actual 880Hz track

Conclusion: everything is wrong. Track1 duration should be 1650 (1500 + 150) and have 150 frames of blank data. Track2 should not have any prepended blank data and no 880Hz audio parts.

I can hear the 440 to 880Hz transition in the 2nd track if I read it with QuickTime. But with iTunes I don't. Maybe there is something worth exploring here.

------------------------------------
------------------------------------

Disc 2

Track 1 : 440Hz sine 1500 frames, 2s pregap
Track 2 : 880Hz sine 1500 frames, 0s pregap

Burned using Express Burn for Windows XP
Extracted with Window Media Player (WAV), dd and analyzed with Audacity

Window Media Player:
Track 1: duration = 22sec (ok), but the blank data is appended (which makes no sense, really) rather than prepended. The track also has ~2 frames a prepended blank data.
Track 2: duration = 20sec (ok). The track has ~2 frames a prepended blank data. This implies that the track is truncated.

dd:
Track 1: size = 1652 frames (should be 1650)
Track 2: size = 1502 frames (should be 1500)

Conclusion: everything is wrong, again.

I have no idea what's going on here. The result depends on which software was used for the burn and which was used for the extraction. The end result is always wrong.

[edgar]

This is going to be a cool puzzle to solve!

At first sight, Toast seems right to me.
The pregap is missing, but can the first track of a CD have a pregap at all?

Are you using an mp3 as audio source? It is a known issue that mp3 files always starts with a blank frame and thus have a pregap (something around 25ms, which is near 2 CD frames). If you'd convert this to WAV and cut it exactly as the CUE sheet describes, it would explain why a little bit of track 1 moves to track 2.

I'll run some experiments too next evening!

[Fabio]

I'm using the mentioned AIF files, which are raw uncompressed bytes.