prob w/ extracting "clean" clips to use as assets

[pauld2007]

Using Cinematize and MPEG StreamClip I thought I was extracting "native" video streams from dvds I've made and avoiding needless re-compression. That's my goal but there is a wrinkle.

I use Cinematize to extract video from unprotected dvds that I've burned. I'll explain why later but I also use MPEG StreamClip to extract the clips from the dvds I've made. An error in DVD Studio Pro seems to point to a discrepancy here. The clips I extract with Cinematize (elementary stream/separate stream files) have data rates of about 7mbs whereas the clips I extract with MPEG StreamClip are 9 or 10mbs. When I use the Cinematize files as assets DVD Studio Pro is happy, when I use files from MPEG StreamClip I get this error msg "Muxer Bitrate too high"

When I need just part of clip of a clip I use MPEG StreamClip and select DeMux to M2 & AIFF, I thought this was a different command for doing the same thing I do with Cinematize, but the data rates show otherwise. Why are the MPEG StreamClip always so much higher?

Thanks,

Paul

p.s. I'm an video editor using DVD Studio Pro for the first time to build a simple "demo reel" dvd. It's worked out pretty well except for this wrinkle. I know it's not an ideal way of moving video to digital but I do it using a good Pioneer video burner DVR-310.

[Frobozz]

The m2v from both Streamclip and Cinematize should be identical in size. Neither can do any MPEG 2 re-encoding. So that would mean the audio streams are different. This naturally would make sense if one is AC3 and the other is AIFF. If both are AIFF open them in QuickTime Pro and choose Show Movie Info to see how the files are different.

[pauld2007]

Hi Frobozz,

Thanks for you reply but I'm extracting separate files so the different data rates I mentioned are from the *video* files, the MPEG Streamclip video files are consistently bigger. Unfortunately the size is making DVD Studio Pro cough up the "Muxer Bitrate too high" error.

Best,

Paul

[Frobozz]

You have me really stumped here. The Streamclip m2v files of the identical clip cannot be larger than the Cinematize m2v files because they are merely an extraction of the original. So something is very wrong for you to get different results. I'm going to experiment with this right now to see if I can get your outcome.

[pauld2007]

Thanks Frobozz,

Though the internal mechanics elude me it's probably worth repeating that I use Cinematize to extract a whole clip that has been burned to dvd as a stand-alone unit. I use MPEG StreamClip when the clip burned to dvd is way too long and I need to trim down and isolate the part I'm interested in. (Unlike Cinematize Pro, plain ol' Cinematize will not keep audio sync with this operation. Since I liked everything about MPEG StreamClip doing this chore, I stuck with it and did not bother with a Cinematize Pro upgrade)

All Cinematize clips I do are around 7mps and all MPEG StreamClip are closer to 10mbs

Paul

[Frobozz]

I'm not having the same experience. I don't have an audio sync issue with Cinematize 2, even when selecting portions for export as elementary streams. My Streamclip trims are identical in size to those from Cinematize of the same in and out points as Cinematize. The ones I've tested this with are 7 mbps avg bit rate with an AC3 audio track. They were originally encoded with Toast 7.

What you are experiencing is extraordinary. I can't think of any possible reason for it to be happening, so I also can't think of a solution. If you did this on a different Mac my guess is you'd get a different result.

[pauld2007]

Frobozz, I'm wondering what would happen if you used a different (non-Toast) dvd and/or extracted and compared a whole extracted clip, no trimming.

Repeating the extraction with Cinematize & MPEG Streamclip on a different Mac (an eMac) I continue to get a discrepancy between the resulting data rates. However it doesn't seem like I can fully trust the data rate info derived from the Get Info window within Quicktime. The same file examined on different machines will display 7863 kbits on one and 959.9 kbytes on another. Allowing for the bit-byte difference, they don't agree so it's undermining my efforts to measure the Cinematize & MPEG Streamclip difference.

Paul

[Frobozz]

I'll do the same test with video recorded by my Pioneer standalone recorder and let you know the result. I know that Cinematize and Streamclip do things differently because Cinematize doesn't use QuickTime for exports whereas Streamclip does. I've found situations where one works for me better than the other -- either way. But that has been with conversions to other formats and not with elementary stream exports.

QuickTime's Get Info is horrible with the accuracy of its MPEG info. I find Streamclip's Get Stream Info to be more accurate but it also has errors. There can't be any actual bit rate difference between the Cinematize and Streamclip MPEG exports because neither of them do any re-encoding when saving as elementary streams.

[AntnyMD]

Doesnt Cinematize "extract" video by transcoding it to DV? If so, DVD Studio Pro will never choke on a Cinematize clip, because DVD SP expects to re-encode the file to spec it likes.

MPEG Streamclip is essentially "keeping it real" here, and is giving you a true duplicate of your DVD.

AIFF audio, which is acceptable in the DVD spec, is also tripping up your clips. AIFF is considered to be uncompressed audio, and eats up a significant amount of the maximum bit rate allowed in a DVD-Video program stream.

[pauld2007]

AntNY MD, you're right that DVD SP liked the Cinematize clips. I think the default with Cinematize is to extract to a DV codec Qt, I override that and select "elementary stream"

The extracts I do (requiring trimming) with MPEG Streamclip are rejected by DVD SP. Based on the Quicktime (player) measure of data rates they are fatter, which seems to explain the rejections by DVD SP.

Paul

[Frobozz]

I think I'm starting to get the whole picture. The next time you try cutting a clip with MPEG Streamclip, first choose Go to Keyframe before placing your in or out mark. Then try that clip in DVD SP. If you edit other than at a keyframe then the surrounding GOP will be nonstandard.

My understanding is the Streamclip streams are being rejected by DVD SP whereas the Cinematize streams are being accepted. However, you are avoiding using Cinematize for small clips because you've experienced audio sync issues.

My recommendation is to use Cinematize for the small clips too, because any audio sync problem with extracted elementary streams should be very uncommon. But if you must use Streamclip, try the keyframe approach.

If you want frame-accurate cutting of MPEG files then you should get Capty MPEGEdit EX. It, however, cannot directly read VOBs so the MPEGs must first be extracted from your DVDs before editing.