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We have a very strange problem with a huge AVI file created by Camtasia. We recorded two days of a conference with Camtasia; both days were ~8 hours long, and people were using two different user accounts on each day. In the end, we found the recorded video from day 1, but not from day 2. And here it gets interesting.
In C:\Users\Day1\Local Settings\Temp there are two .avi files, ~32 GB each, having 8 hours running time, and they contain the screencap from day 1. They seem completely identical. In C:\Users\Day2\Local Settings\Temp\ we have just one file:
ls -l FileWriter8a82d8.avi
-rwxrwxrwx 2 user user 233022109429 Oct 28 16:42 FileWriter8a82d8.avi
(yes, it's 233 GB!)
mplayer FileWriter8a82d8.avi
Playing FileWriter8a82d8.avi.
libavformat version 54.20.4 (external)
Mismatching header version 54.20.3
libavformat file format detected.
[lavf] stream 0: video (h264), -vid 0
[lavf] stream 1: audio (aac), -aid 0, -alang eng
VIDEO: [H264] 1920x1080 24bpp 15.000 fps 2753.6 kbps (336.1 kbyte/s)
Clip info:
major_brand: mp42
minor_version: 1
compatible_brands: M4V mp42isom
creation_time: 2014-10-27 09:20:13
Load subtitles in ./
==========================================================================
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
libavcodec version 54.35.0 (external)
Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
==========================================================================
==========================================================================
Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders
AUDIO: 22050 Hz, 2 ch, floatle, 39.0 kbit/2.76% (ratio: 4873->176400)
Selected audio codec: [ffaac] afm: ffmpeg (FFmpeg AAC (MPEG-2/MPEG-4 Audio))
==========================================================================
AO: [pulse] 22050Hz 2ch floatle (4 bytes per sample)
The runtime of the file (you can seek into it with mplayer, it seems just like a normal file) is also 8 hours and the content is yet again the screencap from Day1. Nothing from Day2 whatsoever.
A quick calculation given the indications: (39 kbps (audio) + 2753 kbps (video)) × 8 × 3600 = ~ 10 GB. So the 8 hours should fit in the first 10 GB of the file.
It seems, then, that there are 223 GB of data on that file that doesn't belong to anywhere. Even if we assume that the actual data part of Day 1 is 32 GB, it's still around 200 GB unaccounted.
Can this invisible portion be recovered somehow? I suspect that the missing Day 2 data might be there. Is there a tool or a program that can scan an .AVI and output complete section info (with offsets) and recover such unaccounted parts of the file?
Another hint is that the disk space was exhausted when I received the machine; it had less than 200 MB available. It's possible that Camtasia ran out of free space at some point during day2, and might have failed to close the file or write the index gracefully.
Posted output is from Ubuntu, but Windows tools are OK too.
anrieff
Posted 2014-10-30T14:09:18.063
Reputation: 191
Sounds like a mistake was made. There isn't anything to recover. Your guess that it ran out of space is very likely. – Ramhound – 2014-10-30T14:14:33.747
Backup the file, open it in VLC and see if VLC offers to fix it. Also try
tacing the file to see if it ends in all nulls or something. – barrycarter – 2014-10-30T15:03:31.360