Question about standalone DVD recorders - AC3 & PCM?

[silentmachine]

Have a quick question about standalone DVD recorders

A friend of mine burned a DVD for me on his standalone DVD recorder. The audio on the disc was AC3. Can standalone DVD recorders record audio to PCM (uncompressed audio)? Do all standalone recorders have the option of either AC3 or PCM? Or does it depend on the make and model of the recorder?

Thanks!

[silentmachine]

OK, I just found out from my friend that the make and model of his standalone DVD recorder is a Sony RDR-GX3.

I don't have access to the recorder but I need to find out how to burn a DVD with PCM sound and not compressed AC3. I looked through the online manual (http://www.docs.sony.com/release/RDRGX300.pdf) but I couldn't make sense the audio settings...maybe ye'd have a better idea?

Thanks again!

[4candles]

When you say "a friend of mine burned a DVD", do you mean "copied a DVD"? i.e. is the original source a VHS tape or a DVD?

[silentmachine]

He has a professional production studio, he had edited the film (which he shot himself on a video camera) on his computer which he then outputted to the standalone player. Not sure what cables/connections he used but he played the film on his computer and recorded on the standalone in real-time.

So to answer your question the source is not DVD, it's from his computer, hope that helps!

[4candles]

Reading the PDF about the RDR-GX300, the specifications (page 88) only list "Dolby Digital/2 ch, 256kbps" in the recording audio formats - so the answer to your original question appears to be no, that particular DVD recorder can't record PCM audio.

But I'm assuming that you are looking for a way to create the best possible DVD (because you are asking about LPCM audio), in which case, I would suggest that you try and avoid using a standalone recorder. Once the video and audio are inside a computer, they should stay there, and PC software should be used to author the DVD for burning using a PC DVD recorder.

Otherwise, you are introducing unneccessary analogue stages in both the video and the audio. You shouldn't have any problem authoring a DVD with PCM audio using PC software.

[silentmachine]

thanks for your advise, but he has trouble with his computer DVD writer and can't use it, but I'll look into fixing that problem. just out of curiousity, what PC software do you use to author DVDs?

[4candles]

Originally Posted by silentmachine

thanks for your advise, but he has trouble with his computer DVD writer and can't use it, but I'll look into fixing that problem. just out of curiousity, what PC software do you use to author DVDs?

Linux - specifically http://dvdauthor.sourceforge.net and http://mjpeg.sourceforge.net

[RainDawg]

I agree...if the data is already on a PC, why send it to a standalone? Doesn't sound terribly professional to me .

There are quite a few nice DVD authoring packages out there, and if he's running a studio he can probably afford to sink a few bucks into a nice package. DVD burners are down to well under $100, so there's really no excuse to not author and burn the video direct from there. Do a google search for 'DVD author software' and you'll find at least 10-15 really nice suites dedicated to this function.

The audio codec will be determined when you compress the video to MPEG-2.

[4candles]

Originally Posted by RainDawg

The audio codec will be determined when you compress the video to MPEG-2.

That sentence doesn't make any sense The audio codec is determined when you encode the audio to a DVD compliant file (maybe compressing, maybe not).

Lots of software may combine some of these steps, but when preparing a DVD, you generally do the following:

1) Encode the video stream (if it's not already DVD compliant MPEG-2)
2) Encode the audio stream (either compress using AC3 or MPEG, or leave as uncompressed PCM, in either case it MUST be either 48KHz or 96KHz)
3) Multiplex the two (or more if you have multiple audio tracks) together to form an "MPEG program stream" - i.e. the contents of the .VOB files.
4) Prepare the DVD "VIDEO_TS" structure ready for burning onto DVD.

[RainDawg]

In my experience, there are generally three major steps in creating a DVD video.

1. Capture (in this case, this info has been completely left out)
2. Compress. This creates and MPEG-2 file and the audio. You will set what bitrate you would like to use for the video, and what audio codec/bitrate to use there as well.
3. Author. This happens once you already have a DVD compliant MPEG-2 file (with embedded audio stream).

So, that sentence does make sense. In step two, you will take the video in whatever format is was captured in and convert (both the audio and video) to a DVD compliant format.

[4candles]

I think we're both just being overly pedantic.

The problem is that the phrase "mpeg file" is very vague - the MPEG standards define (at least) the following types of files:

1) A file containing a single elementary video or audio stream. A ".mp3" file is an example of an MPEG elementary stream.

2) A file containing an MPEG program stream - a collection of video and audio elementary streams multiplexed together, possibly with other data such as subpictures. Used on DVDs (.vob files are essentially a constrained subset of program streams with extra DVD-specific private data).

3) A file containing an MPEG transport stream - similar in concept (but not in structure) to a program stream, but can contain more than one program. Used in digital TV broadcasting.

I always work with the raw elementary streams when authoring DVDs, and then multiplex them together at the very end, when I am ready to author the DVD. Hence when someone says "video file", I always think of an elementary video stream, and not a program stream - which is how this conversation started. I also think of the compression and multiplexing as two distinct steps in the process, even if your software combines the two.

[RainDawg]

Understood, and agreed.

Originally Posted by RainDawg

2. Compress. This creates and MPEG-2 file and the audio. You will set what bitrate you would like to use for the video, and what audio codec/bitrate to use there as well.

Lots of people create separate audio and video streams to use in authoring. Some authoring applications only accept de-multiplexed content.

Originally Posted by 4candles

Otherwise, you are introducing unneccessary analogue stages in both the video and the audio. You shouldn't have any problem authoring a DVD with PCM audio using PC software.

i agree with this statement. there is an exception, however... if the setup is PC > firewire port/cable > standalone DVD recorder (firewire input, which some standalones have), then that would be a digital transfer from PC to standalone.

before any flames come, i did check out the model in question that the original poster mentioned, and i did note that particular model doesn't appear to have a firewire input. i was just pointing out that some standalone recorders do have the (digital) firewire input.

even still, i'd much rather burn a DVD using a PC recorder, regardless, because it's just plain quicker.