I'm not sure if this is a bug, or maybe a setting I can adjust.

The Project Monitor is not updating. I have a short clip taken from video tape that I want to loop. To do so, I need to pick the exact in frame and out frame.

However, I've been going crazy trying to select the correct frames, and eventually I realized that the problem was the Project Monitor is slow to update, so I wasn't selecting the inpoints and outpoints I thought I was.

Even if I go frame by frame it does not update in time. It will go four or five frames, frozen in place, and then suddenly jump to the current frame to catch up.

Can I adjust my memory or display settings in such a way as to cope with this, or is this simply a bug?

Thank you for any advice.

It should step frame-by-frame when paused. However, if you are working with something with B frames, and enabled skipping B frames in settings, it might do what you describe. What format are you working with? Also, depending on the format and speed of your system, it might take a little while to seek, and if you rapidly step or scrub, then it may wait until it things you have settled. But it's not like it just sits around waiting for you to stop. This is a simple refresh queuing mechanism. Each seek event will enqueue a refresh, and when there are multiple refreshes queued, it just processes the last one, waits for another, and loops. You can see the behavior varies proportionally with the complexity and resolution of the format.

ddennedy,

Thanks for your reply and all your hard work on Kdenlive.

I don't know what "b frames" are, so while I assume I'm not using them, maybe I'm just not aware.

The file format is .avi. In the project there is only one clip in the timeline, and no effects or transitions. Should be pretty simple.

And yes, this is happening when I pause and then move frame by frame. I am not scrubbing or sweeping, I'm using the "advance by one frame" button in the monitor.

So to be clear, if I pause the video anywhere in the clip, and then move frame by frame, for about four frames or so, nothing in the project monitor moves.

After the fourth frame or so, the project monitor shows motion, but it jumps to the frame I'm currently on. If I back up, it's the same story.

The thing is, for this animation that I am looping, I am trying to find the start point, as mentioned. Since nothing happens for about four frames, I can't be sure on which of those four frames the animation begins. And, after experimenting a bit, I know that the delay effect is not consistent. the number of frames between when I start advancing frame-by-frame and when I start to see motion can vary between roughly 3 to 6 frames.

So is this a bug?

It probably means your particular AVI format is not well supported. Does it play smoothly or look to be skipping frames? In a terminal window run 'ffmpeg -i the.avi' and show the output here.

$ ffmpeg -i rainbow_01_edited.avi
FFmpeg version 0.5-svn+3:0.svn20090303-1ubuntu6+patch~ppa3, Copyright (c) 2000-2009 Fabrice Bellard, et al.
configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn+3:0.svn20090303-1ubuntu6+patch~ppa3 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libxvid --enable-libmp3lame --enable-libfaac --enable-libx264 --enable-libdc1394 --disable-armv5te --disable-armv6 --disable-armv6t2 --disable-armvfp --disable-neon --disable-altivec --disable-vis --enable-shared --disable-static
libavutil 49.15. 0 / 49.15. 0
libavcodec 52.20. 0 / 52.20. 0
libavformat 52.31. 0 / 52.31. 0
libavdevice 52. 1. 0 / 52. 1. 0
libavfilter 0. 4. 0 / 0. 4. 0
libswscale 0. 7. 1 / 0. 7. 1
libpostproc 51. 2. 0 / 51. 2. 0
built on Jul 11 2009 13:11:02, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 30000.00 (30000/1) -> 29.97 (30000/1001)
Input #0, avi, from 'rainbow_01_edited.avi':
Duration: 00:08:01.77, start: 0.000000, bitrate: 1824 kb/s
Stream #0.0: Video: mpeg4, yuv420p, 714x478 [PAR 211:238 DAR 633:478], 29.97 tbr, 29.97 tbn, 30k tbc
Stream #0.1: Audio: mp2, 48000 Hz, stereo, s16, 64 kb/s
At least one output file must be specified


I see there's a difference in the frame rate of the codec and the codec...? I ripped the video from DVD with HandBrake... I tried to select to keep the original frame rate. Perhaps I screwed it up somehow?

Ugh, this is getting messy quick because there potentially several issues at hand. First, your video very well could be using B frames. It is not untypical for DVD rippers to include them. In a terminal window, run 'ffplay -debug 1 rainbow_01_edited.avi' and in the text output before the 'size:' field in every line (your output could vary from mine), you will see a standalone letter I or P. If you also see B, then your video has B frames. Now, B frames in AVI requires a bit more work in FFmpeg libs to do the right thing. So, that is a possible issue. Since you are using mpeg4 and not H.264, then you do not need to worry about Kdenlive dropping B frames intentionally.

Next, you are working with telecine footage, which upconverts from 24 fps to 29.97. This means it might appear that some frames are repeated esp. when used in conjunction with deinterlace. See this for more information:
http://en.wikipedia.org/wiki/Telecine#2:3_pulldown

If Handbrake can do a "reverse pulldown" or "inverse telecine" and output to something like MP4/MOV for a 23.98 or 24 fps output you might get better results. But you will then see 1 of 5 frames being a repeat of its predecessor if you are doing a 30fps project. Also, look for an option about B frames, and perhaps turn that off.

After you provide more info, I will download Handbrake and try to reproduce your problem.

ddennedy,

Thanks for your hard work on this issue.

I ran the command you suggested, and of course, the output stream was huge. However, I think I can be reasonably sure there are no "B" frames. I scanned the output lines carefully, and there were only "I" and "P" frames as far as I could seen.

Also, just as an extra note... the original footage was on NTSC Beta-cam. I had a professional service convert that to DVD, as that seemed to be the best way to eventually get it onto computer. I'm in the process of getting ride of all old tape-based back ups.

Handbrake has some framerate options. In the current video I have, I selected "Same as source". I'll try ripping it again, with different framerates and see what happens.

Unfortunately, ripping it as an MP4 with 23.976 or 24 frame rate has not changed the problem. I also tried checking the "Detelecine" option as well.

The project monitor does not display the correct frame when advancing frame by frame.

Please let me know if I can provide any more information that might zero in on the problem.

Just some further information.

I can run the same video in AviDemux and other programs and advance and rewind frame by frame no problem.

Not sure if that adds much information, but I thought it might make clear that the files aren't corrupted or anything.