Music Glitch

[bjc]

When reconstructing an existing PTE show today - this time using v 4.30 - I am find my MP3 compressed WAV music file is reading as being the wrong length (?) in both 'music duration' and in the 'timeline'.

In it's original uncompressed form (27MB) PTE reads the file correctly as being 5 minutes 15 seconds in length ~ as an MP3 compressed WAV file (795KB) PTE is reading it as being 4 minutes 12 seconds long.

I have not encountered this problem before. And, by the way, I have doubled checked in my music editing program (Sound Forge) that both versions are the in fact same length - and they are both 5:15 long.

The result of this inaccurate 'music duration' reading is that, as the 'timeline' displays only 4:12, and with the slides are laid out along the span of the music - the music ACTUALLY has another minute to play, so the slideshow comes to an end long before the music finishes.

I have created a new MP3 compressed version of the original music file (on the off-chance that the old one had become corrupted in some way) yet the new one is STILL being read by PTE as being only 4:12 in length.

I have re-created the show using the uncompressed file - and this 'works' perfectly. But repeated attempts at re-producing the show with the (old and new) MP3 compressed file always results in the duration of the music being inaccurately calculated.

I'm not sure whether this problem has been encountered by anyone else (and I apologise if this has already been resolved) however, I wonder what, if anything I can do to put matters right.

Could this be a v4.30 issue ?

bjc

[LumenLux]

I think I would try first to convert your wave to mp3 using a different converting program. I use Accoustica but dbPowerAmp (mentioned recently) is popular and free. If that is what you already use, then try another. Also, can you re-create the problem with any other wav file?

[bjc]

LumenLux

Thanks - I will try various options tomorrow - I'm out giving a lecture tonight (part of which will be related to using PTE for slideshow production!?)

All my previous PTE shows have used MP3 compressed WAV files created using Sound Forge - so, prior to v4.30 things have always worked OK.

I will experiment tomorrow with using a different MP3 compressed music track and see it that 'reads' as being the correct length or not - a very sensible suggestion LumenLux - why didn't I think of that ?

bjc

[LumenLux]

You have also turned over another diagnostic idea of trying the "problem" mp3 file in your show but do it with Version 4.2.

[Guest guru]

Bjc, I am quite sure it's not a 4.30 issue: I made just now some tests again, and all is regular. Are you sure nothing has changed in your audio codecs? Actually there are not programs that convert wat to mp3, but only codecs (used by programs). We use Lame codecs (3.90 - 3.96), and the length of .wav and .mp3 are identical in PTE 4.30 and also in previous versions.

By the way, the size of your mp3 (795 KB) is suspect: if the .wav is 27 MB the Mp3 should be about 2,5 MB at 128 KB per sec., and about 1.3 MB at 64 KB/sec.

[bjc]

LumenLux & Guru

Hi Guys – problem sorted.

On my return from the lecture this evening (having hopefully converted a few more people over to using PTE) I decided to investigate this music problem a little further before going to bed.

Step one was to revert back to PTE v4.10 ~ where I found the problem still existed ~ so clearly it was a ‘music’ issue rather than a v4.30 issue.

So I created a new audio track (44,100Hz – 16-bit – Stereo – file size 31.37MB) and converted it to MP3 (11,050Hz – 8-bit – Mono – file size 438KB). Outside of PTE both tracks played perfectly from beginning to end and were both 3:00 minutes long. In PTE (v4.10 and v4.30) the original track was read as 3:00 minutes long, but the MP3 track read as just 2:29 minutes long. The problem still existed. (?)

It then dawned on me that MAYBE I had forgotten what my previous ‘standard’ was for converting these music files to MP3 --- so I created another new compressed version of the original file using MP3 at 22.050Hz – 8-bit – Mono ~ problem sorted !! The resultant file was only slightly larger than before, at 526KB.

So (my apologies !!) the problem was ME and not PTE ~ I had simply forgotten what settings I’d previously used for MP3 conversion and chosen 11,050Hz instead of 22,050Hz. It’s interesting though that this differential should bring about a misreading of the true music-track length by PTE. All three versions of this new music track (11.050Hz – 22,050Hz and the original) played perfectly, from beginning to end, outside of PTE ~ in fact the 11.050Hz version will play through accurately, right to the end, if ‘keep last slide in show on screen’ is selected – although the timeline won’t allow you position slides beyond the misread music duration. So PTE will play these ‘over-compressed’ (?) files, but is clearly unable to accurately determine their length for some reason. No problem though, providing I remember to use 22,050Hz in the future.

Sorry to have troubled you with this error, which was MINE ~ and I thank you for your feedback which helped me figure out where I was going wrong.

Regards,

Bjc (PS… v4.30 is stunning !!)

[LumenLux]

So (my apologies !!) the problem was ME and not PTE ~ I had simply forgotten what settings I’d previously used for MP3 conversion and chosen 11,050Hz instead of 22,050Hz.  It’s interesting though that this differential should bring about a misreading of the true music-track length by PTE.   All three versions of this new music track (11.050Hz – 22,050Hz and the original) played perfectly, from beginning to end, outside of PTE ~ in fact the 11.050Hz version will play through accurately, right to the end, if ‘keep last slide in show on screen’ is selected – although the timeline won’t allow you position slides beyond the misread music duration.   So PTE will play these ‘over-compressed’ (?) files, but is clearly unable to accurately determine their length for some reason.   No problem though, providing I remember to use 22,050Hz in the future.

Certainly no need for apologies bjc. In fact what you have found is quite interesting to me. I think probably Igor might also be interested. What do you think Guido?

[alrobin]

I had a similar problem in an earlier version with Windows 2000 and mp3's created with the Fraunhofer codec in Cool Edit. Igor and I tested 7 or 8 alpha's before he found a solution, but he did manage to resolve it.

Bic, would you be using Win 2000 by any chance?

There is a known problem with mp3's created with Cool Edit and the Fraunhofer codec in that approx 25 ms of time are cut off of the beginning of the file each time it is read into Cool Edit and then saved again as an mp3. The solution to this, as Guru has indicated, is to use the Lame encoder.

[Guest guru]

Dear Bjc,

I'm glad you solved your problem. But please avoid using so much compressed mp3 files. The more common, "standard" mp3 is 16 bit, 44,100 KHz sampling rate, 128 KB per second bitrate. If your wav file doen't contain high frequency sounds, you can decrease the sample rate to 22,050 (= bandwidth about 10 KHz). But at 11,025 the quality is very poor (bandwidth 5000 Hz, like an old AM radio!). As to bitrate, you can go down till 64, but under this value the sound quality gets worse severely (distortion, artifacts).

So please don't use these extreme values, even if your sound files become very little!

[bjc]

Alrobin,

You are perfectly correct about me using Windows 2000 – that is indeed the OS installed on my ‘Imaging’ system. I’ve just tried putting the same show together using my Windows’98 machine (having transferred all the relevant files across) and the same thing occurs – although that might be down to the fact that the compressed music files were created on a Windows 2000 machine. (?)

I take onboard the point that both you and Guru make, with regards to the Lame encoder – unfortunately it would appear not to be compatible with Sound Forge (?) so I would have to change music-editing software in order to use it –(not the best scenario when you’re already comfortable with a particular piece of software)-however, I will bare it in mind, and if needs must, I will make the change.

Guru,

Thank you for your input – I have to admit that, as an ‘Imager’, I place little importance on the ‘quality’ of the sound –(to me, it’s the images that come first)- and the majority of the compression I do is for ‘voice commentary’ on tutorial CD’s. The PTE slideshows I create are played only at my lectures – using a small pair of portable (and rather pathetic) speakers, so superior audio quality would be barely noticeable. But I take your point, and admit that I made a mistake by compressing to 11,050Hz, I shall stick to 22,050Hz (or higher) in the future. There is clearly no advantage in enabling PTE to ‘read’ audio below 22,050Hz correctly – so the issue is probably best forgotten about altogether – although the fact that this does create problems is worth baring in mind for future reference.

Thanks everyone for your feedback – problem solved !!

bjc

[Guest guru]

Only a little remark, Bjc. Sound Forge mp3's (and CoolEdit too) are perfectly compatible with PTE, if they are correctly encoded in a normal format, no matter that are coded by a Fraunhofer codec. What is not advisable is to use Mp3Pro files, although they can be read by PTE.

P.S. - I too use Windows 2000, which still is my preferred MS OS.

[alrobin]

Yes, Guru is right - there is no problem with timing discrepancies, even in the Fraunhofer-created mp3's, once you get them into PTE. Then you can modify and save the slideshow files as much as you want, and once the synchronization is set on the timeline, it is as accurate as you would want it to be, and also stable, thanks to the folks at WnSoft who worked on it (and especially the adaptation for Win 2000 - dual processor compatibility) for a long time in order to get it right.

The problem occurs when you save as mp3, load back into Cool Edit, Sound Forge, etc., save again, re-load, re-save, etc. One should always create the sound as a .wav file, do all the editing, and saving, of different versions, etc., until one is happy that the file is suitable for the slide show, then save as an mp3 and don't go back into it for editing purposes. If you have to change something, use the last version of the .wav file, and re-save as an mp3.

It's the same thing as with the images - best not to edit the jpeg's, but do all one's work on an original lossless .tif or .bmp or .psd file, and only save as a jpeg when all the editing is complete, unless, of course, as with digital cameras, one is starting with a jpeg. And in the latter case, if making modifications, go back to the original jpeg.

[Guest guru]

Alrobin's explanations are always clear and precise, and reveal all his experience of PTE (and not only PTE...).

I wish to express to him my gratitude for sharing this experience with all of us, and for the generous work he's making in our forum.

Thanks, Al!

[alrobin]

Thanks, Guido! And, you're more than welcome! But no credit to me - I'm just passing on what I learned by listening in to the rest of you gurus!