Sample rate difficulties in exporting to tape

[PVNC]

I've done quite a bit of searching, and I haven't come across a problem quite like this anywhere.

I shoot a fair amount of DV footage, edit it in Premiere 6.5, and save a non-recompressed DV-AVI to HDD for archiving and later encoding. On my camera and in Premiere I practically always use 48kHz 16-bit audio (only used a different sample rate once, and I'll get to that later). I've tried exporting my finished project or the resulting DV-AVI out to my DV camera. When I play back the exported tape on my camera, the audio plays fine. However, whenever I try to recapture it to my computer, no audio is captured. I've tried Premiere, VideoWave, and DVIO - and all capture video with silence. I've checked the properties of these recaptured files, and all have a totally silent 32kHz audio track. This totally boggles my mind. I never use 32kHz.

I've tried exporting my Premiere-produced DV-AVI files to tape using DVIO, with no luck. I also tried WinDV. Here, things got even more confusing. WinDV does not fully buffer these DV-AVIs, and stops sending video to the camera after 0.9 seconds. However, I have one DV-AVI that has 44.1kHz audio. This one does get fully buffered and sent to my camera by WinDV.

After this, I tried exporting from Premiere again, but this time, changing the project audio settings from 48kHz audio to 32kHz, just to experiment. I ended up with 32kHz 12-bit audio on my tape, which I was able to successfully recapture with Premiere. It works, but it's too crude for my liking. I don't want to degrade audio quality just so that I can make a recoverable tape backup.

Yes, I have uninstalled and reinstalled Premiere. Problem remains. Any hints or suggestions would be greatly appreciated.

[Video Dude]

There are some DV cameras that are limited to 12 bit (32kHz) and can't do 16 bit (48kHz).

There are other cameras that have both 12 bit and 16 bit. If you record in 12 bits, then the camera will leave the extra 4 bits so you could "voice overs" during editing. Many cameras default to 12 bit and you have to go into the settings in the camera to change it.

Look in the camera's manual to see if you could even do 16 bit.


Make sure you are saving your DV file with "DV Audio" and not regular PCM. DV Audio has a higher bitrate then PCM at the same settings. 44.1kHz is not a "DV Audio" stream. Under your codec settings you should be see "DV Audio" when you render, don't set it to PCM.

[PVNC]

My camera supports both 32kHz 12-bit and 48kHz 16-bit. I've configured it to always record in 48kHz, and that is the format that my source clips are in. That is also what I use by default when editing and exporting in Premiere.

I've never heard of this "DV audio" format that you speak of. I know that 48kHz audio in a DV-AVI has a higher bitrate than CD-quality PCM (obviously, because the sample rate is higher). I thought DV just used PCM - that is the information I got when I opened a type-2 DV-AVI captured by Premiere from my camera in VirtualDub (48000Hz, stereo, 16-bit, PCM, 1536kbps).

As for rendering or exporting the project in Premiere, when I choose to export in Microsoft DV-AVI format, I have no choice as to audio compressor. I can only export uncompressed audio (which as I said I believe is PCM). Like I said in my original post, when I export the audio as 32kHz, I can recapture it fine. But when I export it as 48kHz, like my source, I cannot recapture the audio.

[Video Dude]

I did a google search to find a screen capture of the "DV Audio" you say you don't have.

This is not my site, but a random site I found that has a screen capture.

*Link removed*

Take a look.

Notice how the the audio format towards the bottom right says "DV Audio". You would select PAL or NTSC.


When I open type-2 in VirtualDub, I see "DV Audio - NTSC".



Some people do say that PCM should work with DV. Others say its not correct to use it. So this may not be your problem.

Rather, it may be something with your camera or even your software settings. Perhaps bring your camera to a friend's house who also has Premeire. Or have a friend bring their camera to your house and try it. That way you can determine if its a camera problem or a software/system problem.

[PVNC]

I've never seen anything in Premiere about DV audio. What program is that screenshot from?

The fact that I cannot even export these files that I've created with Premiere to my camera using other programs (like the fact that WinDV won't properly buffer them) leads me to believe that it's not a problem with my camera.

Later: OK, here's what I believe to be proof. I have an old DV tape of a video that I exported to my camera from my friend's Mac, using Final Cut Pro. This one can be recaptured with audio in Premiere. The file properties of the two test captures I made from it show that it contains 48kHz audio. So I'm pretty sure that my problem lies somewhere in Premiere.

[Video Dude]

The screen is from Ulead MediaStudio. I have used a number of DV programs and they all seemed to have the DV Audio.

I have never used Premiere so I can't be of help with the settings. Maybe someone else will be able to provide some help.

[bb]

Although I'm afraid I can't help with the audio problem, I feel it's necessary to clear this up:

- Sampling rate (32 kHz or 48 kHz) is not the same as sampling precision (12 Bits or 16 Bits). For DV there's 32 kHz @ 12 Bits and 32 kHz @ 16 Bits as well. I believe 48 kHz is usually - if not always - recorded at a precision of 16 Bits per sample.

- Whether or not there's extra space for an additional sound track depends on whether you record in SP or LP mode. There's no such thing as "the extra 4 bits so you could 'voice overs' during editing".

Actually there should be a way to export 48 kHz audio back to the DV camcorder using Premiere. I don't know which setting it is as I don't use Premiere, but it should definitely be possible. Maybe there was something wrong with the DV export right at the beginning. You could try type-1 and type-2, and consult you camcorder's manual regarding the DV-in capabilities.

bb

[Video Dude]

Originally posted by bb
- Whether or not there's extra space for an additional sound track depends on whether you record in SP or LP mode. There's no such thing as "the extra 4 bits so you could 'voice overs' during editing".The phrase "extra 4 bits" is not technically correct but I thought that it was a good visualization to help understand how it works at the time of my first post. I should have said track 1 and track 2. Let me clear up what I meant.

For example:
http://news.sel.sony.com/pressrelease/4076
Quote:
"The model also offers audio recording flexibility with PCM Digital Stereo Audio in 12 and 16-bit audio modes. Sixteen-bit offers high quality stereo sound, while the 12-bit Audio Dub mode records digital video in two stereo tracks for the simple addition of background music or voice-over to the video."

The Sony model I bought a while back has this 12 bit Audio Dub mode. Basically you shoot your footage with 12 bit sound. Then you come back later and can record voice over or add background music. DV cams in 12 bit mode offer two tracks. The second track is left "empty" if you don't use the Audio Dub Voice Over feature or if your camera does not include this feature. You don't need a computer to do this, you plug in a microphone directly into the camera. Its cool because you do the voice over again and again without erasing video or 12 bit track 1 audio.

Check this article out also from 2002 (The section "Camcorder audio dub"):
http://www.camuser.co.uk/articles/misc/200209/200209.php




Edit: PVNC posted a good equation below to show how it works.

[PVNC]

48 (kHz) x 16 (bit) x 2 (channels) = 1536 kbps

32 (kHz) x 12 (bit) x 2 (channels) x 2 (tracks) = 1536 kbps

I believe this means that 1 48/16 track has the same data rate as 2 32/12 tracks.

Anyway, thanks for the suggestion, bb. If I can't find anything, I'll probably check out Adobe's user-to-user forums, too (I don't feel like shelling out $40 US for support to get this fixed, though!).

EDIT: messed up those equations

[PVNC]

Well, I found out a weird workaround. I'll post it here, in case anyone else ever has the same problem.

I opened the DV-AVI file exported from Premiere in VirtualDub, set the video to "Direct Stream Copy" and the audio to "Direct Stream Copy" as well. Under "Audio>Interleaving" I chose to preload 0 ms of audio, and to interleave audio every frame. I then saved a new AVI. I was able to open this AVI in WinDV (which did fully buffer this time) and export it to my camera. I then captured the entire thing on the tape back into Premiere, no problems, and it does have 48kHz audio.

The funny thing is, if I try to export a DV-AVI from Premiere with interleaving every frame in the first place, WinDV won't buffer it. I have to use VirtualDub and write an extra file. This is really bizarre.

[bb]

@Video Dude:
Thank you for the explanation; that's fully correct. But be aware of the fact that the voice over mode @ 32 kHz / 12 Bits is probably not available in LP mode. E.g. my camcorder supports voice over, too, but only in SP mode.

bb

[bb]

@PVNC:
That's weird indeed. Note what happens if you save a type-2 DV AVI through VirtualDub's "Save AVI" function with "Direct Stream Copy" enabled for both, video and audio:

- A DV type-2 AVI contains the audio twice, once intermuxed in the AVI's video stream (vids) and once in the AVI's audio stream (auds). You may say that a DV type-2 AVI's video stream is equivalent to a DV type-1 AVI's iavs stream. The latter contains the audio only once; therefore type-1 files are smaller than their type-2 counterparts.

- After saving the type-2 file through VirtualDub you get a file which is VfW compatible, but it's neither a type-1 nor a type-2 file. It contains a video stream (vids) with video only, and the audio in the auds stream.

I assume this may be reason for the incompatibilities. I don't know whether this is a camcorder or a software (WinDV / DVIO) problem. Unfortunately I cannot test this, because my camcorder does not support DV-in.

bb