Rendering to AVCHD with Progressive Scanning

[Dave Haynie]

[Stephen Coulson] “I want to render to a format as close to my source as possible. When I try to render to AVCHD I am unable to select ‘Progressive Scanning’ and I’m forced to accept ‘Interlacing’ (Field Order: Upper Field First). To get progressive scanning with audio included I’m having to use *.mp4. As my source is in 1080p I don’t want to have to render to 1080i, as I understand it this will lower quality and cause those dodgy lines when panning.”

Well… a couple of things. Check the AVC Profile and other settings. If you’re changing settings but keeping Blu-ray compatibility, you don’t have a 25p option.

I suspect that’s your problem. Blu-ray supports only 50i, 60i, or 24p at 1920×1080. This is less of a problem than you might think, since nearly all modern displays de-interlace on playback (LCDs and DLPs don’t support any form of interlacing at the hardware level). So while the film will be stored as 50i, it’ll play back as 25p most of the time.

-Dave

[Stephen Coulson]

Thanks for the reply Dave,

I hadn’t realised that Blu-ray only supported 50i, 60i and 24p. That would explain the Blu-ray options in Vegas.

One question, considering my source was filmed in 1080 25p would you recommend rendering out to 1080 24p or 1080 50i? Will the fact I will drop a frame every second if I render to 24p cause audio sync issues or will Vegas sort this out?

I’m going to render out the video and audio separately for blu-ray authoring and then use MetaFox to bundle them into MKV’s so I can view them on my HTPC.

Thanks

[Dave Haynie]

I would render the 25p as 50i for Blu-ray. That’s generally what’s done for 30p shot on NTSC cameras as well. On a classic TV, it’ll look find, just with perhaps a more film-like cadance. On a modern TV, it’ll look exactly like 25p, since it will be — modern displays are all progressive, and pretty much any DLP, LCD, or Plasma display is going to upconvert any incoming video into 50p for most DVB countries, 60p for ATSC countries (noting here that NTSC and PAL are both effectively just historical footnotes right now).

-Dave

[Dave Haynie]

[Stephen Coulson] “One question, considering my source was filmed in 1080 25p would you recommend rendering out to 1080 24p or 1080 50i? Will the fact I will drop a frame every second if I render to 24p cause audio sync issues or will Vegas sort this out?”

Vegas will drop frames or interpolate (depending on what you told it to do), so this will technically work. Not what I would do.

It’s also been common for 25p video to be sped up to 24p and delivered in NTSCfilm format (with 3:2 pulldown added to display at 60i as needed) for NTSC countries, commerically. They do pitch-neutral speedup on the audio to fix the audio issues. This would also work, but it’s not necessary, unless you’re trying to target US players as well.

-Dave