Converting webcam footage recording

[zamar27]

What video converter can copy content from this sample media container created in Win 8.1 by Logitech Webcam Software LWS2.80 using DirectShow qcap.dll, to a standard media container like AVI without re-encoding, so it can play in any media player? It contains video 1920х1080 @ 15 fps MJPG и аудио 44.1 kHz 16 bit PCM footage samples from a Logitech webcam. LWS keeps saving into it captured footage until recording is stopped, and then re-encodes it to WMV by using videoC.dll (which likely contains its format description) and deletes. If LWS or PC crashes, the only file recovered is that container with recorded camera footage.

If not a known video converter, can someone suggest any other tool capable of analyzing and converting that file? MediaInfo and Gspot can't analyze it. Logitech didn't post its format anywhere AFAIK, and neither gives any means to view or recover the content, but it merely contains native webcam MJPG video and PCM audio streams. The linked sample is small, pls test it yourself before giving any ideas to make sure they work. Pls make your suggestions detail enough for an average user to reproduce your success.

[LigH.de]

This appears to be a proprietary file format, possibly only known to Logitech. It has a header I don't recognize, which contains some FourCCs.

Unfortunately, your uploaded file is a stub, it contains only 4 KB (one cluster) of valid data, the rest is zero. So you can't recover anything useful, anyway...

[zamar27]

I specially uploaded a small sample instead of real 5-10 hour recordings, since if we understand how to recover a small recording, the same approach can be applied to a large file. The sample is easy to obtain: just exit LWS process tree in Process Manager once recording is stopped, so the native stream recording isn't transcoded to WMV and the source file deleted.

Would it help you to figure it out if I upload a larger file? Besides, the 50MB sample contains a 2 min recording, so how it can contain only 4 KB of combined 1080P @ 15 fps MJPG video and PCM audio.

Since video and audio streams aren't muxed in that container, I wonder if its possible to separate them, and by doing that figure out the chunks size? Once its clear, indexing will be possible.

[DB83]

I did download the 'sample' but since it did not play I did not comment.

I just wonder whether your 'simple' approach in getting this is not doing you any favour. You asked for an avi format yet you posted an avi format which makes little sense.

Surely your capture software allows you to capture without re-encoding ? And if this really is a propriety format only someone with exactly the same setup can help you.

If the software has to re-encode, simply so you can play it, then let it do so and post that as a short sample.

[zamar27]

The sample file has AVI extension since I changed it from .tmp while trying to play, but format is not AVI - if you check its header with a Hex Editor its obvious. The source is captured in that container without transcoding. And how posting here a standard WMV file obtained after the content is transcoded can help in recovering the original footage, given the fact that I know exactly source streams parameters?

The .tmp container is deleted once content is transcoded to WMV, but the file can be recovered with File Recovery software, so its content is the same as obtained by exiting LWS process tree to prevent transcoding (which only starts once recording is stopped).

Setup has nothing to do with footage recovery, all LWS does is capture source footage to .tmp container, and once recording is stopped by a user, it transcodes saved footage to a WMV container to shrink it. If video recovery software (not file recovery) needs exact format info, I don't think you can call it true recovery, since it defeats that definition as in real life format info may be lost and the container header damaged while captured footage remains partially or fully intact - that's why its called "recovery".

[DB83]

But is it transcoding or merely muxing ? wmv is just a container format.

But if you can not post a working sample then no one can help you.

BTW 50 mb for two minutes appears much too small.

[zamar27]

Sorry, the above sample contains about 15 sec footage. Once auto transcoded into WMV by LWS, it shrinks 4 times in size, and as per MediaInfo contains 1080P WMV2 video with variable bitrate and 48kHz WMA2 stereo audio. I doubt that WMV (more accurately ASF) container can hold MJPG source video.

I'll upload both new samples - original and transcoded - a bit later, hope it can help recover footage from the original container, for example if I use Lossless LWS settings, bitrate likely wouldn't change during transcoding to WMV, and may be it can give some idea about source video chunks size. Changing LWS output format settings affects only transcoded output.

[DB83]

Well if you start with PCM(uncompressed) audio and end with WMA2(compressed) audio that can account for a significant decrease in file size.

I will eagerly await the new samples.