Hi, I'm brand new to this whole thing... I'm pulling video from my camcorder, a Sony DCR-TRV17 (old miniDV camcorder) using Firewire. The files pulled off the camera play just fine but the preview is very choppy. Is this a natural limitation of kdenlive at this point? Is it something that only happens on certain cameras?

When I'm previewing (not actually capturing to disk), ffplay uses about 14% CPU (quad core system, so that's maybe 56% of one core? Hyperthreading is off.) and the video stream that appears plays at about 1-2FPS.

From looking at the processes kdenlive has launched, it looks as though it's running dvgrab in interactive mode and writing its video out to standard output - so I guess kdenlive probably launched it by attaching pipes to the three standard I/O file descriptors (sending commands to its stdin, getting responses on stderr, and getting video data on stdout) and passing the video data straight to ffplay.

When I try roughly the same thing at the command line ("dvgrab -i - | ffplay -") it works just fine... When I use almost the same command arguments as kdenlive used ("dvgrab --format raw -i - | ffplay -f dv -") I get the choppy video. From experimenting with those two options (--format raw and -f dv) it seems "-f dv" is the culprit. With it on I see lots of stderr messages ("ALSA lib pcm.c:7223:(snd_pcm_recover) underrun occured 0B f=0/0"), and the sound and video get choppy...

(ffmpeg v0.8, dvgrab 3.5, kdenlive 0.8)

So, I don't know - maybe "-f dv" should just be left out? (Source change? I can't find ffplay options in config.) I'm not sure what format ffplay is using when the input format isn't specified, but it seems to be working...