[MPlayer-users] Digitizing VHS tapes with mencoder

[Ken Bass]

On Tue, Apr 6, 2010 at 10:41 AM, Rolf Ernst
<rolf.ernst at silverlightning.org>wrote:

> On 4/6/2010 12:11 PM, S Andreason wrote:
>
>> Josef Wolf wrote:
>>
>>> I am about to digitize my VHS tapes. Since this are old family
>>> recordings, I'd
>>> like to have the best quality I can get.
>>>
>>>
>> Just my 2 (cents/pence/peso/yen) worth:

I did the same thing as you (except to NTSC), and had a lot of problems with
the audio keeping in sync with the video. Essentially, the sync kept
drifting farther apart as I recorded more.

This was/is a known problem. I was given this link:

http://lists.mplayerhq.hu/pipermail/mencoder-users/2009-November/010945.html

which explained these things, and, finally, problem solved. (FWIW: I found
that just stopping - not killing - the capture process when you have enough,
then running the re-indexing works just the same as letting the capture
continue running.

As for the dropped/duplicate frames: I found that trying -noskip or -vf
harddup to get rid of those actually caused the audio to go out of sync
again. So I just ignored the messages. But, if you get something like "video
buffer full" then your capturing video too fast and without enough system
cache space (note: not mencoder cache!). If this happens then you can get
worried, because you are actually losing real data.

As for the format to convert to "on-the-fly": that really depends on your
machine. If you get the problem above, switch to an encoder that needs less
cpu, then re-encode to your desired format. Note that capturing to raw
audio/video data will generate too much data for disk i/o too handle, and
you will get the above error again.

Finally, one unspoken (unposted) caveat: due to the nature of the VHS
playback, you will probably get damaged or corrupted frames that will
usually show up in a video editor. I use cinelerra, and it would crash, or
simply not load the video, when it found these. Avidemx has a good (but not
perfect) filter to get rid of those.

Okay, so this was far more than 2 monetary units worth. But just giving you
the benefit of many exasperating days of trial and error.

Good luck.

ken