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DVD stuttering in playback

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Ruby Gold
DVD stuttering in playback
on Jul 5, 2005 at 5:31:40 pm

I'm using PPro 1.5 to edit my production, and exporting it via Adobe Media Encoder for authoring in ULead DWS2. The export settings from PPro that I've used are:

Codec: MainConcept MPEG Video
Quality: 5.0 (high quality)
TV Standard: NTSC
Frame Rate [fps]: 29.97 drop frame
Field Order: Lower
Aspect Ratio: 4:3
Frame Width [pixels]: 720
Frame Height [pixels]: 480
Bitrate Encoding: CBR
Bitrate [Mbps]: 8.0000 (high quality)
M Frames: 3
N Frames: 15

After authoring, I burned it on a Sony DRX 500-UL burner at 4x speed from DWS2. The DVD is stuttering some in playback in a few places on a couple different computers. Can anyone help me figure out possible causes for this and some fixes? I want the export/compression to yield the highest possible quality but to have the maximum stability for playing in a variety of set-top DVD/tv players as well as computers. Thanks for any help.



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David Roth Weiss
Re: DVD stuttering in playback
on Jul 5, 2005 at 7:00:07 pm

Ruby,

You did not mention how you encoded the audio portion of your program, whether you used AC3 encoding or left audio as PCM. I'm assuming you did not encode to AC3, as this type of problem seems to usually stem from this issue. Preferably, you should always use AC3 audio encode. Its makes a huge difference, as overhead is exceeded at high data rates if you do not. Lower your video encoding rate to somewhere around 6500 or 6800, and/or encode your audio to AC3 and your problems should go away.


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Ruby Gold
Re: DVD stuttering in playback
on Jul 5, 2005 at 7:24:38 pm

Thanks a lot for this. I did leave the audio as PCM, assuming that's what it should be to achieve the high quality I want. I don't know what "AC3 audio encode" is. I'm assuming it must be a choice under "Dolby," since there are no settings choices with PCM, but I couldn't find it. Also, there are a host of setting choices, including bitrate, etc under Dolby--could you give me some pointers on what settings to choose? Lastly, but importantly--what impact will this change have on the quality of the sound?

The production is being screened before a large audience, so, of course, I want the audio and video quality both to be excellent, but I also don't want it to stutter during playback. I'm concerned about the impact on resolution/quality by shifting video from the CBR of 8 to 6500 or 6800. What is the impact generally? Thanks so much for your help.


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David Roth Weiss
Re: DVD stuttering in playback
on Jul 5, 2005 at 7:46:26 pm

Ruby,

Don't all the settings on your software, but AC3 is a Dolby encode. It is the standard used on all Professional DVDs, so don't worry about it degrading audio quality. Use either 192 Kbps or 224 Kbps settings. You can try to keep your video encode at 8.0 Mbps, and see if the AC3 encode does the trick. But, if you still get skipping, lower the video rate to the 6.8 Mbps I recoomended earlier and you should have no problems.

Good luck, keep me posted...

DRW


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Dave Friend
Re: DVD stuttering in playback
on Jul 5, 2005 at 8:35:17 pm

Ruby,

DVDWS will convert the PCM audio (as exported from PPro) to dolby (ac3) for you if you wish. You can tell DVDWS to not convert ("conform to template" in DVDWS speak) the imported MPEG video.

" I'm concerned about the impact on resolution/quality by shifting video from the CBR of 8 to 6500 or 6800."

You will likely not be able to see much difference - except it won't be stuttering. (That's good, right?)

I assume you are using the Adobe Media Encoder function of PPro to create the mpeg asset that is imported into DVDWS. When you redo the export try these settings in the Video section of the Transcode Settings dialog.
Slide the Quality control to the far right (5.0)
Bitrate Encoding: CBR
Bitrate [Mbps]: 6.800
M Frames: 2
N Frames: 10

Artifacts that might be seen are most likely to occur during fast motion sequences. If your program has a lot of those then consider a VBR, 2 Pass encode with a max rate of 7.500, a target of 6.500 and a minimum of 5.500. But try the CBR first.

An audio bit rate of 192kbps will work just swell for the Dolby encode.

Dave


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Ruby Gold
Re: DVD stuttering in playback
on Jul 5, 2005 at 9:05:36 pm

Thanks for the response, the suggestions are really helpful. I'm sorry that it generated more questions, tho, so...

I see the place in the DWS2 "burn project to disc" window where you can change the audio template to ac3--thanks for that--but I don't see the option to "conform to template."

If I export my program as PCM from PPro, will DWS2 just override that and convert it if I choose that template in the "burn to disk" window or do I need to find the "conform to template" option? And, does that mean the audio is getting "stepped on" twice--to export it as PCM, and then to convert it to AC3?

I noticed in the template for "high quality" with the AC3 option that the audio bit rate is 256 kbps, is that too high (since you said that 192 is groovy)?

Also, I noticed in the template that they have the video data rate as "variable"--is that any conflict for the MPEG asset that I've exported out of PPro at a constant rate?

I have no fast motion sequences in the piece--it's all video of talking heads or brief video sequences with AE effects, and pans/zooms of stills. And, really, the stuttering wasn't terrible--just a couple times, but once is too much, so... do you suggest just shifting the audio and seeing if that does the trick? Or changing both video and audio settings?

Lastly, just for my own edification--what are the M frames and N frames you suggested changing?

thanks so much-
Ruby


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Dave Friend
Re: DVD stuttering in playback
on Jul 6, 2005 at 3:58:38 pm

[Ruby Gold] "but I don't see the option to "conform to template."

The actual terminology that you will see in DVDWS is "Convert to Disc Template". Sorry for not being accurate which created confusion instead of insight.

The "Convert to Disc Template" option is on both the Video and Audio pages (of the Edit Step) meaning that you can choose any combination of A/V to be converted or not. Note that each "video title" you bring into a DVDWS project has this option, so you have to be sure that each asset is being treated the way you want.

If you choose to have the audio converted to the disc template it is indeed processed according that template. Therefore, the PCM file out of PPro will be 'stepped on' again. However, I do not consider it stepped on in the first place (unless you consider mixing being stepped on). PPro is using PCM (as a wav file) and is exporting the same. Since it's all digital once it's in PPro you really aren't going to have the kind of generational loss that we used to work so hard at avoiding in analog days of old. In other words, I consider the audio exported from PPro to be essentially lossless. Therefore, it has yet to be 'stepped on' in the first place.


[Ruby Gold] "I noticed in the template for "high quality" with the AC3 option that the audio bit rate is 256 kbps, is that too high (since you said that 192 is groovy)?"

You can use 256 kb/s if you like and still be much less than PCM


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Ruby Gold
Re: DVD stuttering in playback
on Jul 6, 2005 at 5:06:10 pm

Dave--I can't thank you enough for all this info and support. It has always blown my mind how generous forum folk are with their advice and help. Such a cool thing. Here's a virtual glass of champagne held in toast and gratitude-
Ruby


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David Roth Weiss
Re: DVD stuttering in playback
on Jul 6, 2005 at 10:18:58 pm

Hey Ruby, what about my glass??? Vueve Cliquot I hope...


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Ruby Gold
Re: DVD stuttering in playback
on Jul 6, 2005 at 10:49:42 pm

Now see David--you ruined the surprise. For you--I had a fabulous bouquet of flowers...

Seriously though--I can't thank you enough. Hope I get good enough to return the favor some day.

Ruby


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David Roth Weiss
Re: DVD stuttering in playback
on Jul 7, 2005 at 12:11:08 am

You'll do fine Ruby... Knowing what and where to ask is half the battle. There is a whole load of really good info to be found right on this forum. As is typical of the best forums like this one, somebody is always working on a project more complex than your own, so you can learn what you need to know from them before you really need to know it. Then, when that complicated gig coems in, you're already many steps ahead.


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