Yep, as far as I know mplayer shows a single "aspect ratio" which is the aspect ratio at which the video would be played (i.e. DAR). PAR and DAR in ffmpeg can become quite puzzling since, I guess, both the container and video stream can be reported simulatenously.

mplayer can scale with the appropriate options (i.e. "-vf scale=640:480").

As for the reported dimensions, it displays the video dimensions (actual pixels) not the playback dimensions, which I think is the way to go, since in this context I don't think it matters if the pixels are square or not. If it displayed e.g. 1024×576 for widescreen PAL DVDs it would be lying since 304 of these pixels would be virtual (conversely if reporting 720×405, 171 pixels would be lost in translation). That's just my way of thinking.

I'm sending you an email about the getopt stuff

"…The '<< 1' in this context means 'shift left by one bit'…"

Ahh, of course! I only looked it up on the 'Advanced Bash Scripting Guide' _INDEX_ page, and apparently they overlooked that usage there. Thanks for the clarification.

I've actually been planning some 'bit-banging' of my own lately, so as to swap the field-order in 'd2v-files' used by 'Avisynth' (through 'Wine'), so i should have realised…

The main reason i started digging into your script was to try to modify it to deal with 'anamorphic' video, which includes _ALL_ DVD's as well as any rips made with 'PAR' honoured (like my own x264-encodes). Besides the actual screenshot-resolution being incorrect as things stand, the 'Dimensions' listed in the header also need consideration – atm all PAL-DVD's are listed as 720×576 and all NTSC-ones as 720×480, without honouring the disc's programmed 'display-aspect-ratio', 4:3 or 16:9.

Calculating the correct 'display' width is easy enough – it's either 'frame-width * PAR' or 'frame-height * DAR', but some of those variables appear to only be available through ffmpeg, as is the ability to scale the screenshots as they're taken with the '-s' option (i just realised mplayer might be able to do scaling too, but i haven't tried yet)…

I'd be interested to hear your thoughts on the subject.

On an unrelated note, i have an idea on how to get rid of GNU-getopt, but it might need a long explanation, and this post is too long already, so if you'd like to hear it 'off-site', you have my email-address, or i could post it here at a later date…

Dean

The line you mention is correct although I guess the nested parentheses make it hard to parse.

Emacs is assuming the '<<' starts a heredoc but the '$(( … ))' parentheses are bash's mathematical operator, so what's inside is actually a math operation and not some text.
The '<< 1' in this context means "shift left by one bit". In case you've never seen it, it is a funky way some crazy programmers like me might use to multiply by 2, i.e. "$hv << 1" is equivalent to "$hv * 2". It also means the rightmost bit in the number becomes 0 which is why it's used often in hashing functions (although not in the way I use it).

As for the mplayer+ffmpeg DVD parsing, thanks for the idea, on first look I think I'll be able to use it

Again, thanks for your input and don't hesitate to ask / suggest anything else.

Thanks for this script, it's useful AND educational!

Couple of things; First, is there a typo on line 1075 in the "hash_string" function?

hv=$(( ( ( $hv << 1 ) + $c ) % $HASH_LIMIT ))

…Emacs thinks that everything after the "<<" is a "here document delimiter". If it's correct as is, i'd like to learn its purpose and possibly fix emacs accordingly.

Second, my dvd-drive is useless atm, but i remember previously piping dvd-ouput from mplayer into ffmpeg via a fifo and finding the info generated to be much better than mplayer-alone – for one thing, it won't 'downmix' 6-channel audio automatically. Don't know if that would be useful to you. The syntax was something like:-

mkfifo piped.vob &&
mplayer dvd:// -dumpstream -dumpfile piped.vob & \
ffmpeg -i piped.vob

…See what you think…

Dean

I consider the current version pretty mature and complete so I'll take some time until the next iteration. Of course if you have any suggestion feel free to mail me or comment here.

By the way, if you want to be notified of updates you can subscribe to VCS's freshmeat page.

THANK YOU!

I guess programs will eventually catch up but right now there are many that fail to work flawlessly in Windows 7, specially on the 64-bit version, so I'd recommend you patience and some searching

Best regards!