Out of phase audio in custom synchronisation

[Robin]

Hi there....I am just completing the 4th PTE presentation in the last 12 months. The single audio track I've created (by mixing different MP3's together) is over 10 minutes long. (the longest single track I've done). I am custom syncing the photo's to specific beats in the music therefore the waveform display is essential. however, for the first time I've encountered the following problem.

When setting the points for the slide transitions against the waverform, I've noticed that when the audio is playing, it starts to get out of phase with the appropriate part of the waveform. It starts OK for the first 2-3 minutes and then starts to drift so at the end of the 10 minute show, the audio is playing about 1-1.5 seconds after the same point in the waveform.

I had considered this to be potentially a problem with the sound card (SB Live 128) which I updated over the weekend. (good excuse ) However the problem remains. I have to now interpret the music beat changes by looking at the waveform instead of listening to the audio and then placing transition points. It's offputting and some of my transitions aren't right on the beat because it's very difficult to interpret the waveform without the audio at the same time.

I now suspect its the length of the audio track that could be the problem.

Has anyone else suffered this and is there a solution ?

thanks

[alrobin]

Robin,

Welcome to the Forum!

I have had a similar problem when the transitions were too close together for the computer to process, and the remaining slides got delayed a bit. Otherwise, the timing is normally quite consistent.

Has this only happened with this one mp3 file? You could try substituting another mp3 of similar length to see if there is a problem with the sound file. Also, try spreading out some of the closer images on the timeline to see if this corrects the problem. Are all the images in the slide list represented on the timeline?

[Robin]

Robin,

Welcome to the Forum!

I have had a similar problem when the transitions were too close together for the computer to process, and the remaining slides got delayed a bit. Otherwise, the timing is normally quite consistent.

Has this only happened with this one mp3 file? You could try substituting another mp3 of similar length to see if there is a problem with the sound file. Also, try spreading out some of the closer images on the timeline to see if this corrects the problem. Are all the images in the slide list represented on the timeline?

Hi thanks. Actually the problem is consistent to all slides. some of my transitions are reasonably close together but some are a little wider apart. I have to emphasise the problem occurss in the configuration windows against the wavefile output. The audio gradually goes out of phase so by the end of the 10 minute track....it's lagging the actual waveform display by about 1.5seconds. When I move my transition points to the correct parts of the wave (by identifying those parts in the wave form), the preview and the .exe file run exactly correct....even the quick transitions work OK.

Have to add that the PC is a 2Ghz P4, 1Gig Memory, Sapphire 128M graphics card and Sounblaster Audigy4 sound card.....so all in all, I don't think it's a PC performance issue.

....however....I am considering building a test presentation tonight over 5 minutes and trying it again.

all of the slides are being presented OK. The slides transition with the waveform OK....it's just the audio thats lagging behind which is causing the problem

[JRR]

Robin:

There must be something in the air !!!

I had a similar problem last night. Actually my wife had - she was working on a PTE show (her second) with an mp3 file I mixed for her.

I have done lots and lots of PTE shows and mixed lots of files, but we hit a lulu last night.

The music file came out of Adobe Audition showing a length of 8:02, it showed up in PTE with a waveform on the TIMELINE of 8:02, but the duration (PROJECT OPTIONS>MUSIC>music duration) was 8:34.

Obviously the waveform did not correspond to the sound as it really did go for 8:34.

We solved it last night by going back to the mix and saving it as a .wav form and used the .wav in the PTE file (It is a show that will be seen only 1-2 times so using the larger .wav file is not a problem)

I suspect the MP3 tags were corrupted.

Does your problem have the same characteristics ?

Try another mix as you say and see what happens - use the .wav version and then the MP3 version

[Igor]

Jim,

Please could you send me this MP3 file which shown with the different length in PTE? Write me to int_support@

[JRR]

Igor:

It is on its way.

My wife first thought she had done something to PTE (or PTE had done something to her ) when she was moving slides around within the TIMELINE, but then we discovered the file acted the same way on my computer in a new project.

[Igor]

Thanks.

PTE and well known WinAmp - both show 8:34 for this MP3 file.

Media Player 10 shows 8:02

So I suppose that some low-bitrate and especially non-usual (43 Kbit/s) MP3 files may have problems with detecting their real length. Please use usual 128 kbit bitrate or higher. Or try 48 kbit instead of 43 kbit. Because it better to use default bitrate values like 48, or 64, 96, 112, 128, 160, 192, 256, and etc.

[JRR]

Igor:

I have egg all over my face (my wife through them at me )

I "always" use 128 bitrate.

I remember now that I was showing someone the different compression ratios for mp3 (and comparing them to .psd and .jpg files).

I obviously left Audition set at the custom 40 bit rate and didn't notice it when I made the mp3 tracks

Thanks for pointing out my sloppiness.

Now, for the next point.... What time is it over there ?? You really do need to take a break from PTE you know and get some sleep !!

[Robin]

Robin:

There must be something in the air !!!

I had a similar problem last night. Actually my wife had - she was working on a PTE show (her second) with an mp3 file I mixed for her.

I have done lots and lots of PTE shows and mixed lots of files, but we hit a lulu last night.

The music file came out of Adobe Audition showing a length of 8:02, it showed up in PTE with a waveform on the TIMELINE of 8:02, but the duration (PROJECT OPTIONS>MUSIC>music duration) was 8:34.

Obviously the waveform did not correspond to the sound as it really did go for 8:34.

We solved it last night by going back to the mix and saving it as a .wav form and used the .wav in the PTE file (It is a show that will be seen only 1-2 times so using the larger .wav file is not a problem)

I suspect the MP3 tags were corrupted.

Does your problem have the same characteristics ?

Try another mix as you say and see what happens - use the .wav version and then the MP3 version

Hi JRR....I don't know you but I love you !!!. I went back to Cool edit pro and resaved my mixed audio tracj as a WAV file. Once I used this as the reference audio track, the audio track and waveform now tie up completely and I can move all of my transitions that are in the wrong place. Really....many thanks for coming on here and adding your support. I'm showing the presentation on Thursday so really happy I've got this sorted.

[Ken Cox]

according to my ms time zone feature

kirov time is 1:02:45 am dec 6 05

at

sarnia time of 17:03:11 est

ken

[JRR]

according to my ms time zone feature

kirov time is 1:02:45 am dec 6 05

at

sarnia time of 17:03:11 est

ken

Ken: I know we have Newfoundland time 30 minutes later than the rest of us Canucks, but is Igor really 7 hours, 59 minutes, 26 seconds away from us

[Ken Cox]

well when i did my search for kirov time that is what the time was -- i then entered it into ms time zone and it runs all the time in my systray -- it will show 5 places got to keep track of our friends

ken

see

http://www.worldtimeserver.com/current_time_in_RU-KIR.aspx

[Guest damor]

Hi there....I am just completing the 4th PTE presentation in the last 12 months. The single audio track I've created (by mixing different MP3's together) is over 10 minutes long. (the longest single track I've done). I am custom syncing the photo's to specific beats in the music therefore the waveform display is essential. however, for the first time I've encountered the following problem.

When setting the points for the slide transitions against the waverform, I've noticed that when the audio is playing, it starts to get out of phase with the appropriate part of the waveform. It starts OK for the first 2-3 minutes and then starts to drift so at the end of the 10 minute show, the audio is playing about 1-1.5 seconds after the same point in the waveform.

I had considered this to be potentially a problem with the sound card (SB Live 128) which I updated over the weekend. (good excuse ) However the problem remains. I have to now interpret the music beat changes by looking at the waveform instead of listening to the audio and then placing transition points. It's offputting and some of my transitions aren't right on the beat because it's very difficult to interpret the waveform without the audio at the same time.

I now suspect its the length of the audio track that could be the problem.

Has anyone else suffered this and is there a solution ?

thanks

Like you I'm new to PTE.also like you, had a problem with audio. I tried,after many other things what davegee suggested and that was to rip the audio using media player and audacity. It worked.

Cheers

Dave (damor)

[Robin]

Like you I'm new to PTE.also like you, had a problem with audio. I tried,after many other things what davegee suggested and that was to rip the audio using media player and audacity. It worked.

Cheers

Dave (damor)

hi Dave....I got most of my MP3's from ARES GALAXY and did rip a couple of them from CD's using Media player. I did think that once I'd mixed them using CoolEdit pro and then saved a master MP3 (about 10 mins) long, that this would have resolved any variable bit rate issues.....but obviously not !

Anyway, thx for the reply. I'm likely to do a couple more PTEs in the new year so I'll keep an eye out for this problem.

regards

Robin

[alrobin]

Robin,

One other thing you have to be aware of when using Cool Edit is that every time you save a music selection, you clip off as much as 250 msec from the length of the music (this amount depends on the bit rate you are saving as). This is a peculiarity of the Fraunhofer encoder - it is not a problem with the Lame encoder. So, when working with music files, every time you bring the music back into your sound editor it is important to go back to the original version of the music (unless of course you are working with the file in .wav format). Successive loadings and savings of an mp3 file in Cool Edit will make the music progressively shorter and shorter, thus putting your synchronization off.

[Robin]

Robin,

One other thing you have to be aware of when using Cool Edit is that every time you save a music selection, you clip off as much as 250 msec from the length of the music (this amount depends on the bit rate you are saving as). This is a peculiarity of the Fraunhofer encoder - it is not a problem with the Lame encoder. So, when working with music files, every time you bring the music back into your sound editor it is important to go back to the original version of the music (unless of course you are working with the file in .wav format). Successive loadings and savings of a file in Cool Edit will make the music progressively shorter and shorter, thus putting your synchronization off.

Something else learned today then !!. I don't know the Lame encoder. Is there a preferred choice of wave editor that used this encoder ?

[JRR]

Audacity uses the lame encoder

As you may have seen eslwhere on the forum, when saving in MP3, save at bit rate of 128kbps (96 is acceptable as well)

[alrobin]

you clip off as much as 250 msec from the length of the music (this amount depends on the bit rate you are saving as).

Sorry, Robin, I should have said "you add as much as 250 msec to the length of the music ...". It's been a while since I was faced with this problem myself. Also 250 msec is worst-case. The usual amount is more like 75 to 125 msec.

If you don't want to have to go back to the original music selection each time, and replicate all the changes, it helps, whenever you save an mp3 file, to also save a ".wav" version as well, and then go back to this file when doing further editing.

[Guest damor]

Sorry, Robin, I should have said "you add as much as 250 msec to the length of the music ...". It's been a while since I was faced with this problem myself. Also 250 msec is worst-case. The usual amount is more like 75 to 125 msec.

If you don't want to have to go back to the original music selection each time, and replicate all the changes, it helps, whenever you save an mp3 file, to also save a ".wav" version as well, and then go back to this file when doing further editing.

Well at least I can sleep at night now without have to count beats

cheers

Dave