Quantcast FFmpeg: Letterboxing with FFmpeg (Aspect Ratio) - digitalFAQ.com Forums [Archives]
  #1  
10-02-2003, 04:55 AM
el_mozo el_mozo is offline
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Anyone was succesful transcoding a 16:9 file to a 4:3 *VCD using ffmpeg? By defaults it creates a very stretched image (it doesn't keep the aspect ratio). I would like to add black borders on top and bottom, but looks like I can't (you can't use negative -crop values like in transcode to add black borders).

Maybe there is some option / way to do it with ffmpeg that I couldn't find?

I think ffmpegX for mac/osx does it, does anyone know how?

Cheers
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  #2  
10-02-2003, 08:19 AM
Razorblade2000 Razorblade2000 is offline
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Uhhhmm... this is funny too...
He actually DOES add black borders...
I think he writes sth in the mpeg header...
If you use mplayer in Fullscreen, these black bars disappear somehow... but in windowed mode, they are there...

(I used the "-aspect" parameter)
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  #3  
10-02-2003, 08:48 AM
el_mozo el_mozo is offline
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Quote:
He actually DOES add black borders...
He?? Who is he?? Do you mean ffmpeg or ffmpegX?

Quote:
If you use mplayer in Fullscreen, these black bars disappear somehow... but in windowed mode, they are there...

(I used the "-aspect" parameter)
So, could you paste here the complete ffmpeg command you used? I can't get the correct ratio on the output..

Thisi is what I used:
Code:
ffmpeg  -i /downloads/dvd/movie/file-1-1.vob -s 352x288 -r 25  -ac 2 -ar 44100 -ab 128  -b 890 -minrate 300 -maxrate 2500 -aspect 4:3  -g 18  -pass 1 movie-1-2.mpg
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10-02-2003, 08:53 AM
Razorblade2000 Razorblade2000 is offline
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he= ffmpeg

I think you were using -aspect the wrong way...

I used e.g.
blablabla -aspect 1.85

(blablabla=kwags encoding tip)


so for 4:3 this would be:
-aspect 1,3333

but maybe this is all nonsense
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  #5  
10-02-2003, 09:13 AM
el_mozo el_mozo is offline
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But, the aspect ratio for VCD has to be 4:3, hasn't it?

Anyway, I can't test it until I get home, but, do you get black borders (I mean new black borders, which weren't on the original file) using that aspect ratio?

Cheers
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  #6  
10-02-2003, 10:48 AM
Razorblade2000 Razorblade2000 is offline
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uhhhmmm... maybe...
but as a kvcd-user I don't care much about standards
*g*

Black Borders ARE displayed... but NOT in fullscreen...

EDIT:
Damn... somehow the borders arent displayed on my standalone...
I have to switch manually to 16:9
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  #7  
10-05-2003, 07:26 AM
Razorblade2000 Razorblade2000 is offline
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anything new???
still won't work fine...
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  #8  
10-05-2003, 05:36 PM
el_mozo el_mozo is offline
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I gave up

I couldn't see any difference on the output files, using "-aspect 4:3", "-aspect 1.333", "-aspect 1,333", "-aspect 16:9", "-aspect 1.777" or "-aspect 1,777". Always the same stretched output.

What version of ffmpeg are you guys using? Do you get good (not stretched) output while encoding 16:9 vobs (from DVD) to VCD, or KVCD?

Maybe we'll have to wait for a new ffmpeg version...
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  #9  
10-05-2003, 06:06 PM
kwag kwag is offline
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I always get the full Anamorhpic output ( or the same aspect of my input ). No way to control it
I'm with you mozo. I'll just keep checking every new version every now and then.

-kwag
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  #10  
10-06-2003, 03:34 AM
japie japie is offline
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ffmpeg doesn't add black borders, youll need another utilty to do that job. Maybe there's a way to insert something with the -vhook but I have no idea how. (maybe for subs too)
This is the main reason why I'am using a chain like:
Code:
mkfifo -m 660 stream.yuv
mkfifo -m 660 resized_stream.yuv
mplayer -benchmark -noframedrop -nosound -vo yuv4mpeg -osdlevel 0 $1 &
cat stream.yuv | yuvscaler -v 0 -M WIDE2STD -O SIZE_352x288 -n p > resized_stream.yuv &
ffmpeg -f yuv4mpegpipe -i resized_stream.yuv -an (+ options)...
encode audio seperatly and mux...
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  #11  
10-06-2003, 04:10 PM
Razorblade2000 Razorblade2000 is offline
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do these commands create new files???
or just a kind of frameserving?
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  #12  
10-06-2003, 11:17 PM
japie japie is offline
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Quote:
Originally Posted by Razorblade2000
do these commands create new files???
or just a kind of frameserving?
It's frameserving (or piping).
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  #13  
10-12-2003, 08:44 AM
Razorblade2000 Razorblade2000 is offline
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could you please tell me what each command does? got a lil curious... *g*

Would the mplayer command include postprocessing?
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  #14  
10-12-2003, 10:52 AM
japie japie is offline
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Code:
mkfifo -m 660 stream.yuv
mplayer -noframedrop -nosound -vop scale=352:240 -vo yuv4mpeg -osdlevel  $1 &
ffmpeg -f yuv4mpegpipe -i stream.yuv -an (+ options)...
First we create the pipe:
mkfifo -m 660 stream.yuv
After that we start mplayer to "fill" the stream with raw yuv images; -vo yuv4mpeg, it will serve frame for frame as fast as it's read from the pipe.
-vop scale does the scaling, you can use any mplayer filter in this.
The ffmpeg line explains itself, it only differs from direct encoding that we have to tell it to use a yuvstream: -f yuv4mpegpipe -i streamname
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  #15  
10-13-2003, 01:50 PM
Razorblade2000 Razorblade2000 is offline
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Hmmmm... I somehow can't get any results... always an error
I guess i'll give mencoder a try... should be the same results as ffmpeg...
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  #16  
10-14-2003, 12:38 PM
japie japie is offline
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Currently I'am testing a rework of my mkxvcd script using transcode to add direct dvd ripping (for backup purposes off-course)
I make an post if suxsesfull.
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  #17  
10-14-2003, 03:53 PM
Razorblade2000 Razorblade2000 is offline
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You should really take a look at this:
http://www.kvcd.net/forum/viewtopic.php?t=6822
sooooo many nice options!
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