I thought it would be a simple job. Record a video of me using my Air Hockey program to demonstrate its features. I have spent some time writing a script and recording and editing it in AudaCity. I have generated a number of ogg/vorbis/theora (not sure which is the right term) video files using recordMyDesktop showing the software running, and so all I needed to do was pick video sequencing editor to put them all together and I would be done.
Easy, or so I thought. Wrong!!!
Although I had not used it before, I had been intrigued by Openshot. This became my first choice at trying to assemble my video. It started out fine. I managed to arrange a sequence of two starting images – one the creative commons licence and the second my video title image, and coupled in my sound. As I started adding in the first of my “recordMyDesktop” videos, it became obvious that I would have to stop the video and add in filler images so that my voiceover audio script would not get left behind. But the razor tool allowed my to split the track, drop a snapshot image (created with ffmpeg skipping forward along the video to the time I used the razor on it and creating an image – ffmpeg -i in.ogv -ss 12.4 -vframes 1 -f image2 out.jpg), extend that out long enough for the audio to catch up, and then snap the rest of the video back to back on the track. It seemed to be working great. Until I rewound the video preview one time and Openshot crashed and disappeared underneath me. It was then that I discovered that my project file was empty. There was nothing I could do – all my careful edits were lost.
I did start again, this time hitting the save button manually on a regular basis, but I have to ask myself “Why do I have to do this – isn’t this what computers are for?”. I also decided it would be quite nice to add some background music to the video, particularly there is a blank section at the start before my voice over starts which would benefit from that. So I added an additional track and loaded up the audio file. It was at this point I realised I would need to fade of the volume to about 25% value as the voiceover started so as not to drown it.
It was then I discovered a limitation of Openshot (at least I think it is, and discussion on the Openshot forum seems to imply it was). You can adjust the volume for the length of the clip and you can fade in and out to zero, but you cannot scale from say 100% to 25%. It appears the best you can achieve it to get out the razor and split the audio into small sections and then set a volume for each section.
I didn’t get as far before when it crashed again – although at least this time I hadn’t lost so much. I decided to submit a bug report to Openshot and because of the non ideal handling of volume try one of the other editors I knew was available.
Since my last attempt at making a video had been, I thought, reasonably successful using Cinelerra that was my first choice. Except that before I had been using Cinelerra-CV and there are two packages in Debian and I hadn’t realised this and picked the wrong one. The first problem was that I couldn’t get any of the video clips I loaded into the resource panel to work. After some discussion on IRC, it appeared that the default colour format mode (RGBA-FLOAT) is not supported in Cinelerra and I was recommended to use RGBA-8bit. Doing so made it recognise the videos.
So I started putting together the video in Cinelerra, except I didn’t get very far. As far as I could tell, any attempt to load my voice over script into an audio track caused it to snap to the beginning of the track instead of starting at about 4 seconds in. I tried to ask a question on IRC about this, but since it was morning UK time IRC seemed dead and there was no-one there to ask. I decided to try something else.
I had seen some comparisons between Openshot and kdenlive and so thought that maybe I would give that a go. First impressions were good. It looked easy to use, with a massive arrange of effects. After a bit of playing I worked out how to add some keyframes at crucial points on the music track so that the audio could be smoothly moved from 100% gain to 25% over the second or so that the voiceover came in. I noticed that the voice seemed a little rough – almost as though it had been over amplified, but I took that to be a failing of the realtime display process and assumed it would work fine in final render.
What was more worrying is that as I was trying to extend my single title image out to the 30 seconds or so it was needed for me to finish the audio introduction, that when playing it back it the title would go blank at around 19 seconds. I tried all sorts of things including making four separate video elements from the title picture and slotting them in one after the other. That made it worse. The titles transitioned to black and back again on each video strip. I decided to try and delete them. I deleted the first and the last, but the two in the middle just would not delete. Kdenlive gave an terse error message and left them there. I had to delete the entire video track.
I decided to try a render of the first 40 seconds of the whole video to see if this blanking effect appears on the final output. It did, and what I also found was that the poor sound quality is on the final render too.
I have asked a question on the kdenlive forum about why the image blanking and failure to delete problem is happening, but so far the only response is someone who says he has this too sometimes. Unfortunately I don’t think kdenlive is going to work for me.
I was playing with blender a few weeks ago, to model a staircase and then take a video of walking around and up it. So I thought I could try the video sequence editor of blender to put my video together. There a plenty of tutorials on the net showing how to do that, with loads of nice curves showing how what I presume was audio/video faded in and out.
It must be me, but I could not figure out how to adjust the volume of the audio track at all. I couldn’t find any way to get any curves to appear in the curve editing window, and checking the documentation I could find, both used technical abbreviations I had no idea what they meant, it was generally for the earlier version of blender. I tried asking on IRC, but there was nobody there to help. The other issue was that it wouldn’t display the ogg/vorbis videos – the only way I could get to see it in preview mode was to use ffmpeg to convert it to a different form. I decided to abandon blender and try something else.