lame 3.96.4, goldwave 5.20, winamp 5.621

2011-09-11 16:39:25

hi,

using the above software, i encoded some WAVS to mp3 with the following settings selected using Goldwave:

VBR, 0 HQ, 224-320 kbps, stereo, include CRC

all encodes ok, however the resultant files display the wrong track times in winamp. They are all reported noticeably of much longer duration (does not seem to be a pattern)

inspecting the meta data of the files shows the correct duration

are there any known issues with this behavior that anybody has seen ?

it's the first time i've come across this personally

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #1 – 2011-09-12 06:30:50

Correction - lame 3.98.4

I tried fixing with mp3val using the GUI frontend, it reported the following errors, but winamp still displays erroneous increased track times. It shows wrong times in the enqueue window, but shows correct times when viewing file info:

Analyzing file "Z:\My Music\MUSIC\MORE_MUSIC_XIV\richard groove holmes\comin' on home (2m)\groovin' for Mr G.mp3"...
WARNING: "Z:\My Music\MUSIC\MORE_MUSIC_XIV\richard groove holmes\comin' on home (2m)\groovin' for Mr G.mp3": Wrong CRC in 1 frames
WARNING: "Z:\My Music\MUSIC\MORE_MUSIC_XIV\richard groove holmes\comin' on home (2m)\groovin' for Mr G.mp3": VBR detected, but no VBR header is present. Seeking may not work properly.
WARNING: "Z:\My Music\MUSIC\MORE_MUSIC_XIV\richard groove holmes\comin' on home (2m)\groovin' for Mr G.mp3": No supported tags in the file
INFO: "Z:\My Music\MUSIC\MORE_MUSIC_XIV\richard groove holmes\comin' on home (2m)\groovin' for Mr G.mp3": 9777 MPEG frames (MPEG 1 Layer III), no tags, no VBR header, CRC
Done!

Winamp file info (correct time):
Payload Size: 8013409 bytes
Header found at: 0 bytes
Length: 286 seconds
MPEG-1 layer 3
224 kbps, approx. 10962 frames
44100 Hz Stereo
CRC: Yes, Copyrighted: No
Original: Yes, Emphasis: None

i ran moonbases vbrfix program and and it fixed the times. in all 3 test files it added exactly 417 bytes to each file (?)

any ideas why/how to avoid this issue ?

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #2 – 2011-09-12 09:05:55

The likely cause of this is that the VBR header was not added to the files. In this case the only way to determine the exact duration of the stream is to scan through the entire file to find out number of frames. This can be a time-consuming process, so the player probably just scans for a few frames at the beginning of the stream and tries to take a guess (and the guess is incorrect in this particular case).

The different times are shown in different Winamp windows probably because it uses different routines to compute the file duration (quick but imprecise for playlist and slower but more precise for file info).

As for how to avoid this, there's nothing much you can do except use different software for encoding (or fix the headers afterwards, like you already did). Try to save the files from Goldwave as PCM WAV and encode them with the command-line version of LAME.

Another way would be to use strict CBR mode for encoding. In this case each frame in the mp3 file has the same size, so the VBR header is not needed to determine the correct duration.

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #3 – 2011-09-12 15:42:58

Well, I must admit that this is the first case that I have come across where the CRC in an MP3 file might have actually been useful.

Ordinarily I would recommend against its use as a waste of space, but here it seems to be showing that something modified or added a frame without setting a proper CRC value.

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #4 – 2011-09-13 10:36:38

thanks for the insights - i think i'll save myself a headache and stick to CBR with consistent times ;-)
i doubt i'll hear the real world differences BTW VBR and CBR
i would much rather have a library with consistent times - it's all about a compromise in the end...

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #5 – 2011-09-13 15:40:42

So you don't need gapless playback?

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #6 – 2011-09-14 04:43:37

Gapless playback was a property I never knew of until I now researched it.

From my readings I don't require it for leisure playback of audio.

Using winamp I have always just employed a buffer and fade on song completion, but I was under the impression using lame files in winamp after 5.3 supported gapless playback? Or is this not the case with a VBR file?

lame 3.96.4, goldwave 5.20, winamp 5.621

Reply #7 – 2011-09-14 08:56:40

The presence of VBR header is mandatory for gapless playback (whether the actual stream is VBR or CBR), because this header contains information on delay and padding introduced by encoder, and there is no reliable way to deduce this information from the mp3 stream itself.

Goldwave probably uses LAME library for encoding, but for some reason does not add VBR header to the encoded files. I'd suggest you to find another frontend for LAME, or just use the command-line executable.