It took ages and effort to get Kdenlive work in the first place. Now having paused for ~4 weeks and wanting to continue I am stuck agin ... trying to Add Clip gives the error message "FAILED TO CREATE PROXY CLIP":

ffmpeg version 0.8.4-4:0.8.4-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers built on Nov 6 2012 16:51:33 with gcc 4.6.3

*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
Input #0, mpegts, from '/home/hlan/Desktop/Cameoscope/PRIVATE/AVCHD/BDMV/STREAM/00000.MTS':
Duration: 00:00:48.97, start: 0.801678, bitrate: 25075 kb/s
Program 1
Stream #0.0[0x1011]: Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
Stream #0.1[0x1100]: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s
Stream #0.2[0x1200]: Subtitle: pgssub
Unknown encoder 'libmp3lame'

In the log we see that ffmpeg is rather recent (6 Nov 2012) and the problem is perhaps related to a Package Manager software update? At the end it says "unknown decode libmp3lame" therefore perhaps this issue can get fixed by just finding libmp3lame package and installing it - but before I mess things up even more, does anybody know what happened and any advise about fixing this issue?

Thank you very much in advance...

Proxy Clip generation works fine for me with Ubuntu 12.10. Although I see you're on 12.04 LTS. The ffmpeg error messages are nothing to be concerned about. I'd look at whatever proxy profile you're using and tweak it. Maybe your proxy profile uses mp3 audio, try using different audio codec or -acodec copy instead. Yes need to fix the libmp3lame problem installing it via your package manager, in fact do that and your proxies may work again as is.?

1) libmp3lame is installed and re-installing did not fix this problem. Maybe something happened to ffmpeg (that apparently requires the library to be enabled at the time when ffmpeg is installed? How can I re-install ffmpeg with all the whistles and bells that it requires to work for Kdenlive?

2) At the moment my Kdenlive encoding profile for proxies is the default:
-f mpegts -acodec libmp3lame -ac 2 -ab 128k -ar 48000 -vcodec mpeg2video -g 5 -deinterlace -s 480x270 -vb 400k
What would be a simpler and more robust profile to use?

Thank you very much in advance,
hlan (worried about what else with Kdenlive may have auto-destroyed itself...)

You could check if libavcodec-extra is installed it may have some effect on what's available to you, also maybe delete the kdenliverc file in your home directory and rerun kdenlive start up config.

The kdenliverc file is in home .kde/share/config I think.

Proxy profile could be mjpeg with a bitrate of 4000k perhaps in an avi container, aduio maybe -acodec copy. All depends on your source files and PC performance.

Wow, thank you so much - impressive where you get that knowledge from ... libavcodec-extra put it back on track!