mp3 header information wrong

jrazz wrote on 8/17/2008, 8:17 PM
At my church we use Vegas 5 to record the audio for the sermons. Sometimes (not always) the length of the sermon will show as significantly less than what it really is.

Here is an example.
Edit: You will want to right click and save.

Two questions: 1. Anybody know of a program (free?) that can correct the header information to show the correct length? (This affects conversion to m4p for ipod downloads as it obeys the information in the header while windows media player doesn't).
2. Anybody know why this would happen on occassion? We use the same custom template week in and week out for sermons. Nothing more than a capture and encode to mp3 as mono with a low bit rate.

j razz

Comments

richard-courtney wrote on 8/17/2008, 9:06 PM
Just wanted to confirm your knowledge of the clip:

says length is 41:09 Mono 40kBit/s rate and plays for 44:50

is your project 48kB/s?
jrazz wrote on 8/17/2008, 9:38 PM
00:44:50.388, VBR, 32,000 Hz, Mono, MPEG Layer-3

44,100

Where did you see the length stating 41:09? In Windows Media Player it shows up as 12 minutes and some odd seconds.

j razz
richard-courtney wrote on 8/17/2008, 9:47 PM
Nero player.

I found a MP3Utility and it says:
MPEG Info:
File size: 12,456,128 bytes
Offset to first valid header: 576 bytes
MPEG 1.0, layer III; Sample rate: 32,000 Hz
Bitrate: 128 kbps
Channel mode: Single Channel (mono)
Private: No; CRCs: No; Copyrighted: No
Original: No; Emphasis: None

Frame size: 1,152 samples/frame
Frame length: 576 bytes/frame (unpadded)
Pad size: 1 byte(s)
Estimated frames: 21,624
Estimated time: 12:58 (778 secs.)

ID3v1 Tag Info:
Tag version: 1.0
Title: 10-06
Artist: Ephesians 4 9
Album:
Year: Genre: Other
Comment:


Processing: C:\test\Ephesians 4 9-10-06.mp3

No errors found.
Summary: 74,733 total frames processed (0 padded, 74,733 unpadded). Bitrate is VARIABLE.

Bitrate summary (excludes VBR header frame, if found):
32 kbps: 41,436 frames, 55.4% of total
40 kbps: 23,386 frames, 31.3% of total
48 kbps: 7,161 frames, 9.6% of total
56 kbps: 2,012 frames, 2.7% of total
64 kbps: 576 frames, 0.8% of total
80 kbps: 152 frames, 0.2% of total
96 kbps: 8 frames, 0.0% of total
128 kbps: 1 frames, 0.0% of total
160 kbps: 1 frames, 0.0% of total
Average bitrate (actual): 37.0 kbps over 74,733 audio frames.




I will send this to a teenager expert on MP3s and see what he thinks.
Chienworks wrote on 8/17/2008, 10:56 PM
Great internet helpline comedy skit ...

(After 15 minutes of frustration and getting nowhere) "Sir, is there a child in the house? There is? How old is she? 9? Great, may i speak with her for a moment? Hi Beth. Hey, we need to get your dad's TCP/IP and PPP settings fixed for him. Would you take care of that? And while you're at it can you make sure that his Outlook Express is configured to use the 3rd party dialer? All done? Thanks Beth!"
richard-courtney wrote on 8/18/2008, 6:42 AM
Kelly you're no help.

Windows Media Player (9) plays it as 38:09. My Nero player plays length something
else. The MP3Utility (geocities.com/mp3Utility) says a third length.

It is time to pass it on to someone who spends hours each day with MP3's.

The variable rate is making it hard to calculate for any program.
jrazz wrote on 8/18/2008, 6:58 AM
RCourtney,

Thanks for your time on this. If your teenage guru has any answers that would be great. If anyone has any ideas on how to fix the header information (as I assume that is where the problem lies) I would be most greatful for a link.

j razz
johnmeyer wrote on 8/18/2008, 8:37 AM
It shows as 38:09 in my Windows Media Player 8.0 (an early version of the "modern" WMP). However, in the Windows Media Player classic, it shows as 12:58. It also shows as 12:58 in MusicMatch.

I looked at the MP3 tags using MusicMatch, and you haven't inserted any MP3 tags. I highly recommend you use software that inserts these tags, either during encoding, or after the fact. Without these, iPods and other MP3 players won't be able to sort these and play them in order according to date, title, author, etc.

The file also has a really AWFUL odd-order harmonic AC hum extending all the way out to 540 Hz. Hopefully that is just a problems with this one file. If not, that surely needs to be fixed. I'd say that it is considerably more important than your MP3 file header problem.
jrazz wrote on 8/18/2008, 8:59 AM
That hum is due to how we are ingesting the audio. It is going in through a cheap sound card built into the MOBO (The whole PC costs less than 199USD). Nothing we can do about that until a new sound card/PC is in the budget.

In the past we didn't think this issue with false times to be an issue but now we have found out it does cause an issue with ipods when iTunes converts the file (I assume they convert it. I don't use the program or own an iPod).

John, we did add some information for the tag later on including the author and church.

Has anyone else encountered this while making mp3's from within Vegas? Ours does it maybe once out of a three month span or so.

j razz
johnmeyer wrote on 8/18/2008, 9:39 AM
The hum is not due to the cheap sound card. It is due to a ground loop. I know funds are tight, but purchase an isolation transformer and insert that between the soundboard and your computer. Should solve the problem. Probably less than $50.

In direct answer to the original question, I have not encountered this problem with Vegas, but I have encountered all sorts of little "quirks" both with Vegas and with other programs when encoding mono MP3 files. Of course if you record in stereo, you'll have to double the bitrate to get the same audio quality, and you probably don't want to do that.
jrazz wrote on 8/18/2008, 9:48 AM
Thanks John.

The signal goes through a limiter into the board and then out via an adapter (1/4" to 1/8"). I think the problem probably lies there.

j razz