TMPEnc Audio conversion problems.

[SMHarman]

Help

Using Camcorder AVI footage as the input. This was edited on iMovie and the output streamed back to a MiniDV tape.

This tape has been pulled onto my MSXP PC by firewire and then encoded into DVD format PAL Widescreen using TMPGEnc.

The pictures are perfect, the sound is metalicised and slow sounding.

Tried using tooLame instead but the same problem. tooLame says it is converting 16-16 and 32,000 - 48,000.

Camcorder is set to 16 bit. AVI file looks and sounds OK on the PC.

[FOO]

Is the sound in sync ? probably not.
What does AVIcodec say about the audio. ?
I think DV audio is supposed to be 48000 pcm.
You might open it in Vdub and save WAV and see if it sounds OK

[SMHarman]

"Is the sound in sync ? probably not."

Roughly - as I said it sounds so poor it is difficult to tell if it is in sync (perfectly).
I encoded an element of one of the files (from the middle of it) and the sound converted OK and in sync)

"What does AVIcodec say about the audio. ? "
Don't know will try it tonight.

"I think DV audio is supposed to be 48000 pcm. "
Thats my understanding also., so what tooLame is doing looks right.

"You might open it in Vdub and save WAV and see if it sounds OK"
Thanks for another suggestion. If I can get an OK sound extraction at 16bit 48k then I can use that and the TMPGEnc MP2 and make a working DVD.

Oh and the sound sounds the same whether PCM or MPCompressed encoded.

Thanks - anyone else?

[FOO]

Toolame doesn't look right. What's the 32000 - 48000 about ?
That's not a resample is it ?

[bugster]

Help

tooLame says it is converting 16-16 and 32,000 - 48,000.

Thats resampling. Tmpgencs resampling is not the best. You can use ssrc.exe instead. Plugs in to TmpGenc in the same way as toolame.

For future footage (assuming this is your own) set your DV cam to record audio in 48khz rather than 32khz to avoid the resampling stage.

[SMHarman]

Help

tooLame says it is converting 16-16 and 32,000 - 48,000.

For future footage (assuming this is your own) set your DV cam to record audio in 48khz rather than 32khz to avoid the resampling stage.

Gets instruction manual - I thought it was set at 48. This could be the problem. Resampling something that does not need resampling.

Some of the tools mentioned allow a strip out of the PCM from the AVI. Perhaps I should do that and use the file as is (I think thats possible).

[SMHarman]

Just had a look at the camcorders specs on the canon web site

http://canon.brochurelibrary.com/getFile.php?productid=6985&languageid=1

Its either 12bit 32khz 4 ch or 16bit 48khz 2 ch.

Why / Where would the audio encoder be picking up that it is 16 bit 32khz, I would guess that this is what is screwing the sound up!

[FOO]

The sample rate will just make it sound funny, The
sample quantizatiion could make a complete mess out of it.
Maybe the codecs don't realize that Canon has used a
strange format.

[SMHarman]

The sample rate will just make it sound funny, The
sample quantizatiion could make a complete mess out of it.
Maybe the codecs don't realize that Canon has used a
strange format.

Newbie question

Sample rate - thats the 32Khz or 48Khz the number of times the sound is sampled/sec

Quant - 12/16 bit? WHat does that do. The number of bits used to record that sound.

Looking at other camcorder specs the 12/32 and 16/48 seem standard, its the file on my PC that is showing up as 16/32. Most confusing. Can I force tooLame to work at 16/48 and see what the result is?

Further thoughts - its not changing the bits, just the rate. Now if the rate was 48 in the first place not 32, then it will interpolate another 16k of information so the sound shoud be running at 2/3 or normal speed or sound slowed down. This is what is happening, so I would think the sound conversion is going wrong as the software is trying to resample a file it just needs to strip out (as it is at the correct rate).

Is what I am writing making sense?

[FOO]

Assume you have a sine wave (pure tone) at 16 Khz.
You take 2 samples per cycle , and get a list of numbers
at 32 K sample/sec. Then you throw your sine wave away.
The problem is to generate a new list of
equally spaced numbers with 4 samples everywhere there were
3 before, just as if you had sampled the original sine wave
at 48 Khz. Its not trivial to determine what the in-between
values ought to be. You can't just interpolate.

And the 12 vs 16 bit numbers
12 bits can represent 4096 different values
16 bits can represent 65536 different values.
The error measuring a real value will be worse with the
12 bit numbers.

[MpegEncoder]

Help

tooLame says it is converting 16-16 and 32,000 - 48,000.

Thats resampling. Tmpgencs resampling is not the best. You can use ssrc.exe instead. Plugs in to TmpGenc in the same way as toolame.

For future footage (assuming this is your own) set your DV cam to record audio in 48khz rather than 32khz to avoid the resampling stage.

I have a Sony TRV-320 and it doesn't have a setting for audio sample rate. It's always 32k.

Also, I upsample to 44.1K all the time with TMPGEnc and it sounds fine. And I'm very picky about audio quality.

Make sure to set the environmental setting under "Audio Engine" to "High Quality". "Low Quality" will definitely suck.

[SMHarman]

What does AVIcodec say about the audio. ?

It's blank!

File : 9.43 GB (1020 MB), duration: 0:46:44, type: AVI, 0 audio stream(s), quality: 50 %
Video : 1020 MB, 3051 Kbps, 25.0 fps, 0*0 (), dvsd = Sony Digital Video, Supported

But Windows Media Player plays the file with its sound.

[FOO]

That's weird . OK what does Virtualdub say ?Surely
something can identify that audio.

[SMHarman]

That's weird . OK what does Virtualdub say ?Surely
something can identify that audio.

Virtualdub wants some codecs that are not on my PC. Didn't know where to go looking or have the inclination last night. Suggestions appreciated.

But...

I took the iMovie files into WMM and did some minor editing. Chopped the 5 seconds of black off the front, a similar 30 seconds off the end and a few seconds here and there off other transitions. I had already had success from a test 5 minutes in the middle of the tape a couple of days ago so thought this just might work.

Saved the AVI back to my HDD and encoded the audio MP2 and video as two elementary streams to put onto a DVD. This time it encoded the audio perfectly and the video is in sync when the two are bundled together on the disk.

I guess IMovie had some strange coding when it saved onto the DV tape and loaded onto the PC that was confusing the audio into thinging it was 16/32 not 16/48 and thus recoding.

The audio conversion took about 5 minutes for a 30 min file, so I can't imagine it was doing any recoding.

Hopefully the problem will not reoccur as I will be doing all the work on one PC going forward.