Batch Processing 2.34:1 AVCHD Files for preview

[goanna300]

I shoot Anamorphic with my Panasonic GH2. The 1.3:1 adapter gives the normal 16:9 an extra squeeze so that it can be un-squeezed in post and authored to a letterboxed blu-ray.

That work-flow is fine - once I know which files I want to edit with. But what I really need first is some way to batch-process the whole lot of a day's shots for previewing. Destination formats such as AVCHD folders would work for me, - or mpeg2 - both will play on my TV with the detail I need to scrutinize them.

Any help appreciated. (Linux if possible)

[Khaver]

Would a batch file using ffmpeg with a combination of scaling and padding filters work? Scale down vertically the amount you need to unsqueeze your video then add padding to the top and bottom to bring it back to 1080 and set the output codec as desired.

[goanna300]

Would a batch file using ffmpeg with a combination of scaling and padding filters work? Scale down vertically the amount you need to unsqueeze your video then add padding to the top and bottom to bring it back to 1080 and set the output codec as desired.

That's almost exactly what I'd imagined. I was sort of hoping somebody else in my situation might have already prepared a script all ready to go!

[aedipuss]

sounds unnecessary and an extra encoding step prior to final rendering. pop them all in your editor and edit as is, then render to the final output. most editors allow adjusting the size of the source files after import(usually right click/properties).

are you shooting 1080 24p or 60i?

[goanna300]

sounds unnecessary and an extra encoding step prior to final rendering

I shoot 24P.
These are my rushes. At best I shoot at 4:1 (discard 3/4 of what I shoot). This is normal. These days without film it's also normal to view in the field while the light, talent, location are there. I can take a notebook on a shoot as well as a monitor. Rendering my rubbish shots would be time consuming. Not getting the shot right would be unacceptable. Getting the talent to do another safety take is no longer necessary with digital.
Even back in the studio, I would rather have my PC do a quick viewable conversion while I'm doing something else.

[aedipuss]

if it's just for viewing try opening one with vlc. click on the video tab/aspect ratio/change the view to 2.35/1

[goanna300]

I've tried VLC and Movie player in Linux and windows, pictures freeze. Media player classic works but is unstable. I remember using something with VOB files which would change an aspect ratio with one number. I just wish I could trick a modern LCD into thinking the vision is anamorphic and that it's displaying it in 4:3. (The unsqueeze ratio is identical between 4:3 and 16:9 as it is between 16:9 and 2;35:1)

[poisondeathray]

try mpchc on a windows box

[aedipuss]

could you upload a small sample to check?

[goanna300]

.. what I really need first is some way to batch-process the whole lot of a day's shots for previewing.

Well, I thought I'd exhausted all the previewing via software options - an indeed I had. Media Player Classic Home Theatre gives similar results. Tweaking a lot can bring up a nice picture, which will play - once. No pausing. Often no sound. It's a dancing bear solution.

After considering an analogue monitor with nice trim-pots to shrink the screen height, playing with my notebook's OS screen height options, watching the monitor through an anamorphic lens, etc, etc...

what I really need first is some way to batch-process the whole lot of a day's shots for previewing.

[poisondeathray]

You should be able to do it with ffmpeg and batch or bash scripts, but you need to figure out the crop and resize values. If you don't know how, post a sample

[poisondeathray]

What are your computer specs ? If your listed specs in your profile are up to date - Athlon64 3000 it's not going to cut it. That would explain your playback issues.

[goanna300]

could you upload a small sample to check?

In the clip, the fireplace dimensions are 39cm x 20 cm

[goanna300]

Thanks for the processor advice: you may well be right about on-the-fly rendering.
I really would like an elegant solution to use while I'm tripping over wires and coping with flies and heat.
I'd be prepared to open up a new, small Panasonic Viera monitor and permanently change the aspect ratio to cinemascope.

[poisondeathray]

Re-encoding it is going to take days on that processor.... seriously think of an upgrade. You would still have the same playback problems if you re-wrote the AR information, probably dropped frames and sync issues

Doing it in realtime with a media player IS the elegant solution IMO

In the mean time, check if this looks ok

The active image area is resized to 1920x816 which gives 2.3529 AR, letterboxed with 132px top and bottom . Is it not wide enough ? or too wide ? Once you figure out the values you want, then you can use pad and scale in ffmpeg


So an example windows batch script that encodes all the MTS files in a folder using ffmpeg and those letterbox values that encodes to mpeg2, with audio copied, into a transport stream. The ouput files will have the same name, but .m2ts extension

 
 
for %%a in ("*.mts") do ffmpeg -i %%a -vcodec mpeg2video -qscale 4 -s 1920x816 -vf pad=1920:1080:0:132 -acodec copy -f mpegts %%~na.m2ts
 
pause

If you want it wider or narrower just adjust the values and compensate with the pad values. I arbitrarily selected qscale 4, but if want higher quality, larger filesizes use a lower value like 1 or 2. If you want lower quality, use higher values

Cheers

[goanna300]

Re-encoding it is going to take days on that processor....
The active image area is resized to 1920x816 which gives 2.3529 AR, letterboxed with 132px top and bottom . Is it not wide enough ? or too wide ? Once you figure out the values you want, then you can use pad and scale in ffmpeg

Cheers

Thanks! The image looks about right from here. I'll try that script later. (I still have that Athlon desktop PC somewhere but rarely use it!)

[aedipuss]

if you go into vlc settings(all) and change the monitor pixel aspect ratio to 0.75 it will display all video as 3:4. the sample plays fine with a q6600 cpu.

[goanna300]

the sample plays fine with a q6600 cpu.

Even simpler.
My next notebook will be a faster CPU than my present dual core 2200.
Right now, I operate on the YDNIY (You Don't Need It Yet) principle. I'll be using a render farm for any real crunching but a faster PC wouldn't be used for much right now.
I notice there's a 22" Panasonic Viera model selling for ~$200. It only consumes 20 watts and I'd be quite prepared to void my warranty and tweak the horizontal size, just to have an insert SDRAM card>preview monitor solution.