Getting HD Footage to "Smart Render"

[Dennis Vogel]

Ah, life was so much simpler with SD, wasn't it? I shot DV footage, set my project properties to "NTSC DV (720x480) 29.970 fps" and used the "Video for Windows (*.avi) NTSC DV" template and everything worked great. Especially, the smart rendering for untouched parts of the footage. How satisfying it was to see that "No Recompression Required" message as my rendering raced through.

Now, I'm trying to figure out how to best match Project Settings and Render templates for some HD footage I captured from YouTube. I have an .mp4 file and GSpot tells me it 1280 x 720, 29.97 fps, 44100 Hz audio along with some other parameters. I only have to trim some stuff off the beginning and end of the video so I'm looking for a way to guarantee a "smart render".

I set my Project Properties to the "HDV 720-30p (1280x720, 29.970 fps)" template and changed the audio sample rate from 48000 to 44100.

When it came to rendering, I got bewildered by the number of mp4 options available. I went with the "MainConcept AVC/AAC (*.mp4) Internet HD 720p" template because it was the only 720p mp4 template that matched my Project Settings as indicated by the "=" Vegas shows next to the templates. Unfortunately, this isn't all that is needed as my entire clip was recompressed; no "No Recompression Required" message.

So, the question is, what's the right way to match source video with Project Settings and Render Templates to endure no recompression is required, not just for my current project but for HD footage in general? I'd like to avoid recompression both to maintain the quality I have as well as to speed up the render.

D

[Leslie Wand]

1. not everything smart renders

2.match project settings with source using properties page icon.

3. render back out to those settings. if it smart renders great, if not.....

[Seth Bloombaum]

Leslie is quite correct on all counts.

Originally Posted by Dennis Vogel

When it came to rendering... I went with the "MainConcept AVC/AAC (*.mp4) Internet HD 720p" template because it was the only 720p mp4 template that matched my Project Settings as indicated by the "=" Vegas shows next to the templates. Unfortunately, this isn't all that is needed as my entire clip was recompressed; no "No Recompression Required" message.

I don't think this is going to happen the way you want. There's a definite hint above, "Internet HD". That indicates a bitrate suitable for internet distribution, that is probably different than your source.

But even if you matched these bitrates, you're starting with a lossy distribution format... Possibly one of the specialty MPEG editors/converters like Womble or MPEG Streamclip might do the trick for you.

[Nicholas de Kock]

The problem with lossy codecs like the .mp4 compression is that it has a variable bitrate and every time you render the variable bitrate is slightly different to the previous version. In order to properly execute a Smart Render your rendering setting have to match the source footage exactly which might be impossible with what you are trying to do. Best overall workflow is to use a more stable codec like Cineform if you want to Smart Render. I've seen even when I Smart Render the Sony EX codec it still does a render every other second because of the different variables. DV is a more stable I-Frame codec, today's HD is very compressed.

[Dennis Vogel]

Variable bit rate. That's the key I was overlooking. Like I said, with DV it was all so simple.

Oh well, I can live with the recompression. It'll just take a while longer to do what I want to do.

Thanks all for the insights.

D

[Laurence Kingston]

Vegas only smart-renders interlaced. I smart-render 30p mpeg2 regularly, but it has to be done with the 60i templates or it won't work. My Sony HVR Z7 U has a 30p mode in it's interlaced potions. That one will smart-render. The 30p mode in the progressive options will not. 30p flagged and smartrendered as 60i still looks like 30 p so don't worry.

[Robin Davies-Rollinson]

I was pleasantly surprised last night to see that my .mxf material (ungraded and just straight cuts) was being smart-rendered as .mxf output. It was all progressive as well.