Old 11th March 2011, 07:15   #1
Vad3K
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Join Date: Mar 2011
Posts: 2
"Jump to time" is slightly off with VBR mp3s

I made a mix-cd (one 80-minute VBR .mp3 file, and .cue file that contains track names / start times for audio-cd burning purposes).

When I open this file in Winamp 5.601, right-click on Seeking Bar -> Jump to time, and enter "9:42" (the start time of 2nd track of this mix from the .cue file), Winamp correctly displays the time "9:42" on the clock, but actually play the music from an incorrect position; it seeks to about 5 seconds before the actual 9:42 position is. If I use the "Jump to time" feature again, and enter "9:47", or just scroll the Seeking Bar to this time, it will display 9:47 on the clock, and play music from the correct position (where 2nd track actually starts).

When I try seeking to starting positions to other tracks (3rd, 4th, 5th...) it is also off, but by different amounts every time. Usually it is off by about 5 seconds in either direction, but sometimes gets up to 15-20 seconds off. These seem to just be random, and not related to where the tracks are in the mix (closer to beginning or end).

The total time of this file shows correctly in the playlist, and also correctly in the Alt+3 info window (Length in seconds). This mp3 was created by using Lame v3.98 encoder (which to my knowledge is the best one), command line "lame.exe -V 2 <filename>". I ran the tools VBRFix and MP3val that locate/fix VBR errors - no change.

I tried my other .mp3 mixes, older versions of Winamp, and running on another computer - same issue.

I then re-exported this mix as .wav, and Winamp was now correctly jumping to its track positions. Assuming the problem is the VBR mp3 format (or mp3 format in general).

I also converted the time 9:42 into milliseconds (582000 milliseconds), and then ran the command-line tool CLAMP with argument "/JUMP 582000", which makes Winamp seek to this position - same issue.

I would like for this to be working correctly for a project, where the program reads the artist/track names and start times from .cue files, displays the list of track names on the screen, and when double-clicked on a track to have Winamp open the corresponding .mp3 file and seek to the correct position, so that the selected track would start playing.

Any ideas ???
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Old 11th March 2011, 08:54   #2
DrO
 
Join Date: Sep 2003
Posts: 27,873
mp3 seeking is not frame / position exact and never has been as to get exact seeking is very cpu intensive so a close-match is done which shows up more so when dealing with vbr mp3's.

-daz
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Old 11th March 2011, 18:08   #3
Vad3K
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Join Date: Mar 2011
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Thought so. Thank you.
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