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Best route from AVCHD or MP4 to Vegas?
Hey again everybody!
I have what’s a pretty straight forward and simple question, but I imagine the answer will be a bit detailed. I am going to be purchasing a Panasonic G6 soon. It can record video in AVCHD, Progressive AVCHD, and MP4. I want to use the camera to the max, so I will be shooting in 60 fps 1920 x 1080. Of course, I will be editing and rendering the final cut from Vegas.
I am unfamiliar with AVCHD, and I’ve only used MP4 to render to. I have noticed that when I import an MP4 file into Vegas, it plays back in a staggering manner, its hard to scrub accurately, drag the ends of clips to the exact right place, etc. It seems to drop a lot of frames. When I finally render it back out, it looks fine, but working with MP4 files inside of Vegas seems to be a problem. So, I thought I would just use the AVCHD format, however, in the specs for the camera it states that the MP4 format actually has the highest bit rate (28 mbps vs. 17 mbps), so that has me thinking I should try to use the MP4 format if I want the absolute highest quality I can get out of the camera yes?
I have been reading up on intermediate file formats, which seem like a pain in the butt, and the idea of re-encoding scares me a bit. Maybe I just need a better h.264 encoder/decoder? (note: I still can’t download the latest version of quicktime from apple. I have no idea why but when I click on the download link, nothing happens. So I have had to use an older version of quicktime as it seems to be all I can install). However if an intermediate format is the best way to go, that’s what I will do. I was reading up on Neo Scene as an intermediary format for the AVCHD files. But it hasn’t been updated in 2 years. My guess is something better has come along?
So what do you/would you guys do in this situation?
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6 Replies
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Just saying MP4 does not describe what is inside the file, but most MP4 files have the AVC codec.
AVC takes a lot more compute power to decode and higher bitrates and/or frame rates just make that even harder. That can cause playback issues with source files of this class.
For example, on my machine, 2.9Ghz i7 my GoPro 1080p30 20Mbps files can playback smoothly, but 1080p60 30Mbps files cannot. Both in the MP4 container.
I use the Vegas smart proxy feature as needed for source files beyond what my machine can handle in Vegas 12. The proxies are mpeg-2 format which is pretty easy to decode.
You can use intermediate formats also. GoPro Studio can convert to Cineform AVI files. This is what replaces the NeoScene software. There is DNxHD for Quicktime. In Vegas 12 you can try HDCAM SR Lite as an inter format.
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FWIW, My lowly i3 540 dual core CPU Intel box with 4 gigs CAN display one 30 mbps GOPRO MP4 24p videostream in preview mode with NO probs or flicker, although at 70% CPU Capacity.
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Your problem is certainly in decoding performance. MP4 is actually just a file wrapper, but the expected content is AVC video and AAC audio. The MP4 file wrapper itself is derived from Apple’s Quicktime, it is not a problem itself as an editing format. Cameras generally resort to generic MP4 to deliver something that exceeds established formats. MPEG-4 is really a collection of technologies used to create complete specs, not any kind of end-user spec itself. Vegas does edit most MP4 configurations, but there’s no guarantee.
AVCHD is a specific format, originally derived from Blu-ray by Sony and Panasonic, as a camcorder recording format that could play on Blu-ray players. For 1080p60 at up to 28Mb/s, you’re talking AVCHD 2.0, which won’t necessarily play on BD hardware. This is another container format, MPEG-2 transport stream (same thing used for ATSC television), holding video as AVC and audio as AC3.
Anyway, the thing that trips you up is AVC encoded video. This is very CPU intensive to decode. Using the best decoders on my old Intel Core Duo 2.4GHz laptop, I saw about 95% CPU used just to come close to a realtime decode of 1080p60 28Mb/s video. Using the GPU under Windows 7, this was reduced to about 8% CPU. I point these out to illustrate that you can’t really judge Vegas preview performance from anything you see in a player.. Vegas doesn’t used those APIs for preview. And secondly, you can count on needing that whole Core 2 Duo 2.4GHz worth of computer power, minimum, just to decode a single AVC stream in realtime in Vegas. Which means, if you don’t have more than that, you really can’t expect AVC editing to work very well. This is why quite a few of us here have higher end systems.
Sony recommends a 2.0GHz multi-core CPU for any kind of HD editing. I’d push that to at least four cores and 3GHz for effective AVCHD or 1080p60 editing. Keep in mind that whatever your resource use at 1080p30 or less, doubling that frame rate also doubles you resource use.
Short of a faster PC, you will probably want to change something to edit well on your existing PC. Transcoding to an intermediate format is one way.. you convert to a simpler, but probably much larger, video format. Some use Cineform for this; other options are high bitrate MXF MPEG-2 (built-in to Vegas), or Avid’s free DNxHD. It might also be possible to use an I-Frame only AVC, which is a format class (“AVC Intra”) you find on newer cameras (my Canon 6D does this).
The other way is a proxy edit.. this goes way back. PCs in the 80s couldn’t handle full rez video, so you’d convert to a preview format, edit that, but swap in the final for rendering. This can be done manually, just by rendering out simpler video, then changing files around. And there are aftermarket tools for Vegas, like GearShift, that automate this.
AVC delivers about twice the coding efficiency of MPEG-2… a 28Mb/s AVC stream should be transcoded to at least 56Mb/s MPEG-2, though its common to use 50Mb/s. The complexity of decoding AVC is much more than 2x that of MPEG-2. But enjoy it.. the next big thing may be HEVC, which can deliver twice the coding efficiency of AVC, but at many times the complexity.
-Dave
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Thanks for all the info, guys! Very helpful.
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Compared with AVCHD, I thought MP4 is more compatible with Vegas since AVCHD is highly compressed.Based on this thought, I recorded MP4 videos via Sony camcorder. However, the mp4 videos were played blurry after importing to Vegas. Some guys on professional forums told me that the problem lied on its codec. Finally, I need to rewrap MP4 videos to MPEG-2 so that Vegas can afford. That’s a huge work for me. Luckily, the tool supplied by those professional guys is much helpful. Save my life!
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transcode is not very recommend , because the conversion progress will lose quality even you cna’t tell with your won eyes. But if you really have no ideal how to put your files into Vegas, then convert them to MPEG or other comaptible frmat.
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