I have got a Sanyo Xacti VPC-CG20 AVCHD video camera, http://sanyo.com/xacti/english/products/vpc_cg20/spec.html, and am now looking at editing the video on my Linux Mint system. Last time I did any editing in Linux was a few years ago, and I used Kino to edit video shot on a Sony DV Handycam, but I see there are a few new options including Kdenlive and OpenShot, both of which I'm going to try out.

First problem, though - I can't get the videos from the camera to play smoothly enough on my computer to edit. They (technically) 'play' in some players (gxine, dragon player), but they are extremely grainy and jerky, and the video won't play past one or two frames in other players (e.g., VLC). The videos were recorded in the highest quality available on the Sanyo camera (1920 × 1080 (60 fields / sec., 16 Mbps).

I'm guessing that this is a limitation of my not-exactly-cutting-edge computer hardware, a P4 2Ghz, 1GB RAM with a NVIDIA GeForce4 MX 420 video card, which though old was more than adequate to play and edit DV from my old Sony Handycam in Kino.

So, my question (and yes, I am aware that the easy answer is probably "get a new computer, buddy!!"): How do I go about converting the video to something that can be edited in Kdenlive on this machine? I don't need to produce the highest quality output (most common output will be DVD or to upload to youtube, low quality is OK). I'm looking at Handbrake as a GUI tool to do this; is there another/better way?

Thanks

-- BV

You can transcode your clips directly in kdenlive. Import them, select them, right click and have a look at the DNxHD transcoding profiles.

To put things in perspective, my 2.4GHz Core2 Duo with 3 GB RAM sometimes struggles with 720p/60fps AVCHD video on kdenlive, usually when playing sections of the project with transitions and special effects. I wish I had a nitrogen cooled 5GHz 8 core CPU instead ;-). However I have become accustomed to that behavior and I don't bother to convert from AVCHD to a less demanding format before editing.

To add another perspective, I'm using an AMD Athlon 64 Processor 3200+ (that's single core, 2 GHz) with 1 GB RAM as well, so my hardware is less than average, too. But I replaced my graphics card with a Geforce 8400 GS, which is not really cutting edge ;-) but works fine with the vdpau drivers. Playback of AVCHD clips is fine for me, but just as tidris pointed out, the system struggles with transitions and special effects. Searching is also poor. Yet the complete setup is usable for me, I also became accustomed to its weak points, and I'm happily working with it.

Cheers

Chamo

Delay in answering; first I had problems posting a reply as I was being asked to type in a Captcha but no Captca was being displayed, then real life intervened . . .

@Chamo, thanks for that tip - from other reading I had got the general sense that a better video card might not make a difference because the editing software had to explicitly use the graphics card memory to make a difference, and only certain (commercial) programs did this; didn't know about VDPAU - assuming it does the same thing to allow the graphics card to do some of the hard work? If I can spend $60 on a video card that will let me edit AVCHD directly, that sounds like a good solution. I'm not doing this professionally, can live with quirks.

I have played around a bit with ffmpeg to see what I can do with the AVCHD source to transcode it to something I can use on my computer with minimal quality loss. As I'm only interested in producing DVD quality at present (this is strictly amateur home movie stuff, and no one I know who might be interested in videos of my family at the cottage, or of my friends mountain biking in Copeland Forest, owns a Blu-Ray player (or if so they can damn well watch a DVD), so I can quite safely lose quality from the original without a care in the world.

So, thanks for the suggestions, looks like I'm going to have to do some reading on what exactly the numbers mean, and, more specifically, what the implications will be of changing the different numbers in the DNxHD profiles actually does. I looked at the transcoding profiles in Kdenlive as suggested by @ttil, but I'm not sure what each one will produce something I can edit in Kdenlive. I note all the profiles there are 1920x1080; I would have thought that the first thing to change to make the video easier to work with would be to reduce the resolution, e.g. to 1280x720; is that right? This is what I experimented with using ffmpeg, and was able to get some playable decent quality transcodes using the "-s hd720" switch in ffmpeg.

I also note Sanyo refers in the specs to "fields per second" and uses the abbreviation 'fps', which I though generally stood for 'frames per second'. The wikipedia entry on digital video cautions about confusing the two; http://en.wikipedia.org/wiki/Digital_video#Regarding_Interlacing, noting fields per second is double frames per second for interlaced video. As if the various elements of digital video weren't complex enough, I cannot tell from the Sanyo menus whether "30 fps" means 30 frames per second or 15 frames per second. Grrrr. Assuming the latter, I'm going to try shooting in one of the lower resolutions on the camera, "1280x720 60fps" and see if that will play; if not, will keep going down . . .

-- BV

Does your camera shoot DV as well, some HD cams have DV modes so you can use them at standard def. If you're going to DVD then this would save heaps on storage, time editing and reducing the burden. Just a thought.

No video mode called "DV"; The camera has the following modes:

Full-HD 1920x1080 60field/s
Full-SHQ 1920x1080 30fps SHQ
HD-HR 1280x720 60fps HR
HD-SHQ 1280x720 30fps SHQ
TV-SHQ 640x480 30fps SHQ

Only video shot in the bottom two will actually play on my computer, so I'll switch it to the HD-SHQ mode for now (until I get a new computer).

I'm now trying to transcode my existing Full-HD footage to something I can use. I tried transcoding using the following transcode profile "-s hd720 %1.mpg", which I would have thought would produce something like the HD-SHQ, and it was horrible, very pixelated, must be missing something there. Best looking output I've been able to get so far is using the following profile "-target ntsc-dv %1.dv", though I think I'm going to have to experiment some more.

Thanks for your suggestions/input.

-- BV