Once again Andrew Gee has come up trumps and cranked out another screencast for the Ubuntu Screencast Team. The latest one is a nice short video showing how to share files and access shared files using SAMBA on Ubuntu. We’ve tried a few new things in this screencast and would appreciate comments on them.
We now have some simple static introduction slides rather than diving right into the demo. All screencasts can benefit from a bit of “chalk and talk”, so we’ll likely keep this for other videos.
We’ve recorded this one in a whopping 1280×720 – which may well become the standard for the future screencasts we make (depending on feedback 
). The nice thing about this resolution is that it’s widescreen (which looks gorgeous) but also it’s a good resolution to play on an high definition TV at 720p. When scaled down it’s surprisingly readable too.
We have also made it available in no less than three downloadable formats. MPEG4, MOV and of course OGG. We also have full size streaming flash, and all of those at three resolutions, 1280×720, 968×544 and 640×360, which should hopefully be suitable for people with just about any connection speed, computer type or screen resolution. The MPEGs should play okay on Windows or Linux (given necessary codecs), the MOVs play in Quicktime on Macs (and AppleTV?) and the OGGs of course should play natively on Linux. We now have a nice scripted conversion system based on ffmpeg which can take a source video and spit out all the variants pretty quickly (depending on CPU of course).
Feedback as always is very welcome. We’d like to know how we can improve things, we don’t mind a bit of criticism
Edit: Comments already received include:-
- MOV audio quality is worse than the other files. I don’t know exactly why this is, I’ve used the ffmpeg options below:-
/usr/local/bin/ffmpeg -i $1.avi -vcodec h264 -s 1280x720 -b 300k -r 10 -acodec mpeg4aac -ar 22050 -ab 128 -f mov $1_h264_aac_1280x720.mov/FFmpeg version SVN-r9450, Copyright (c) 2000-2007 Fabrice Bellard, et al. configuration: --enable-gpl --enable-pp --enable-pthreads --enable-libvorbis --enable-libogg --enable-liba52 --enable-libgsm --enable-dc1394 --disable-debug --enable-shared --enable-libxvid --enable-libfaac --enable-libmp3lame --enable-libx264 --enable-libfaad --enable-libtheora --enable-x11grab --enable-swscaler --prefix=/usr/local libavutil version: 49.4.1 libavcodec version: 51.40.4 libavformat version: 51.12.1 built on Jul 4 2007 21:14:05, gcc: 4.1.3 20070629 (prerelease) (Ubuntu 4.1.2-13ubuntu2) Input #0, avi, from '20070704_samba_filesharing.avi': Duration: 00:05:00.6, start: 0.000000, bitrate: 672 kb/s Stream #0.0: Video: mpeg2video, yuv420p, 1280x720, 104857 kb/s, 24.00 fps(r) Stream #0.1: Audio: mp3, 48000 Hz, mono, 64 kb/s Output #0, mov, to '20070704_samba_filesharing_x264_aac_1280x720.mov': Stream #0.0: Video: libx264, yuv420p, 1280x720, q=2-31, 300 kb/s, 10.00 fps(c) Stream #0.1: Audio: libfaac, 22050 Hz, mono, 0 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream #0.1 -> #0.1 [libx264 @ 0xb7dfa188]using SAR=1/1 [libx264 @ 0xb7dfa188]using cpu capabilities MMX MMXEXT SSE SSE2 Press [q] to stop encoding frame= 2982 fps= 13 q=6568959.0 Lsize= 12323kB time=298.0 bitrate= 338.8kbits/s video:11711kB audio:536kB global headers:0kB muxing overhead 0.613808% [libx264 @ 0xb7dfa188]slice I:249 Avg QP:20.52 size: 31692 [libx264 @ 0xb7dfa188]slice P:2733 Avg QP:22.44 size: 1501 [libx264 @ 0xb7dfa188]mb I I16..4: 87.2% 0.0% 12.8% [libx264 @ 0xb7dfa188]mb P I16..4: 1.7% 0.0% 0.0% P16..4: 5.0% 0.0% 0.0% 0.0% 0.0% skip:93.2% [libx264 @ 0xb7dfa188]final ratefactor: 38.22 [libx264 @ 0xb7dfa188]SSIM Mean Y:0.9962346 [libx264 @ 0xb7dfa188]kb/s:321.7The "0 kb/s" next to libfaac doesn't look good :S
7 Comments
Great work (and results) regarding Ogg Theora.
It would be nice if the source code of the entire script was made available, unless it’s already out there…
Thank you!
The method I use for compiling ffmpg (from upstream cvs snapshot) is here:-
https://wiki.ubuntu.com/ffmpeg
And the script can be found here:-
https://wiki.ubuntu.com/ScreencastTeam/FfmpegConversion
I can’t possibly imagine 300kbit/s video under ANY codec at 1200 by something looking good. You either need to bump up the bitrate or lower the resolution.
Also, please use 2-pass encoding with x264 — the quality improvement is very substantial
Thinking about it, is 300K going to be okay for the lower resolution ones, but higher bitrates for higher res ones? Maybe 300K for the smallest, 600K for the next and 900 for the biggest? Maybe 300,400,500?
Of course given this isn’t a fast moving DVD rip, but a screencast with very little movement, is 300K really that unreasonable?
Thats useful to know. I’m still learning myself, so these kinds of tips are very helpful.
Greetings Alan!
Drop me an email for some gstreamer-based love in terms for encoding, transcoding and support for a new (and open) codec!
Best regards…
MacSlow
OOoo you tease
Will do!