ffmpeg Letterboxing.

[Scorpio1974]

OK, I'm not a noob, but I've been struggling with this manual letterboxing lark for a while now.

Previously I've been encoding my files using the ffmpeg preset, setting 16:9 ratio and using 'decode with quicktime' to add the necessary black bars top and bottom. No probs whatsoever, and I have authored many dvd's in DVD Studio Pro.

Now a 2 hour movie takes a fraction over 4 hours to encode using this method ( yes I know thats pretty quick but I want quicker!!). Using ffmpeg without decode with QT its virtually real-time encoding, which is what I'm after.... so here's my 'problem':

I have an AVI file thats 640x256 (2.35:1), so if I'm to letterbox this to 720x480 what manual padding values do I enter? I do not want padding on the right and left of the movie, I want the movie 'scaled' so its the full width of the frame. So if the AVI is being scaled up, how do I calculate the top/bottom padding pixel size? Or am I being dense here??!!


Many mant thanks in advance..!!

[csdesigns]

Why are you adding the letterboxes? All you need to do is to encode with the DVD 16:9 preset size option. This will make your encoded MPEG-2 anamorphic, and when you use it in DVD SP, you can then set it to the proper display ratio in the track's settings. You can even burn it to an anamorphic DVD, as most DVD players have a setting for how to handle anamorphic content, automatically placing the letterboxes on your 4:3 TV. This will result in a much higher quality looking DVD BTW.

[Scorpio1974]

Aha!!

Well I've never confessed to being very proficient in DVDSPro, and to be honest I was unaware of that feature, but if thats the case, Halleluja!!

Right I'm off to try some stuff.....

Thanks loads, help is really appreciated, especially when the question was obviously a stupid one!!!!

[Scorpio1974]

Ok, I imported my 2.35:1 movie into dvd studio pro after I had encoded it at 16:9, but I can't see a way to add any letterboxes in DVDSP....the movie is stretched vertically to fill the 16:9 space. Am I missing something incredibly obvious??

Any help would be appreciated from people who have been through this already....!

J

[csdesigns]

After encoding your 2.35:1 source to 16:9 MPEG-2 in ffmpegX, you should have a MPEG-2 file that has letterboxes on it when opened in QT Player. This normal. (DVD specs only support 16:9 or 4:3, so for wider sources, you either have to do Pan-and-Scan or letterbox.) Now, take that video track and import it into your DVD SP Assets. Next, select the track you plan to add it to in the Graphical area, and then go to the Track settings and under General>Display, change the mode to 16:9 Letterbox. Now, drag the MPEG-2 video to the track and it should come up in the viewer as a 16:9 track with letterboxes as it looks in QT. When you burn the DVD and play it in a STB, the DVD player will automatically (with the appropriate STB player settings) add the extra letterboxing needed to fill a 4:3 screen and maintain original PAR. This is pretty basic stuff and you should really read the manual (if you've got one).

[Scorpio1974]

Thanks for that, I realise this must be 'basic stuff', and yes, I have read the manual, but I think you have misunderstood me... when I have encoded the file in ffmpegx using the ffmpeg setting without 'decode with quicktime', the original 2.35:1 file become vertically 'stretched' to fill a 16:9 area. Obviously if I use the 'decode with quicktime' setting (which therefore takes twice as long to encode) then quicktime adds the necessary black bars top and bottom and I can import that no problem and everything is hunky dory.... what I'm trying to explain is that when I use the ffmpeg codec and DO NOT add any manual letterbox values then the movie becomes vertically distorted, also the resulting 'mpv' elementary stream that it outputs cannot be opened by Quicktime so I have no idea what you meant when you mentioned 'view it in quicktime'. Are you presuming that I have used 'decode with Quicktime'?

When I do add manual letterbox values, I always end up with a file that is too large for dvdsp to import, as if ffmpeg is simply 'adding' the black bars top and bottom but it still alters the vertical video size.

This must seem simple, but its really beginning to frustrate me that it looks like I'll have to use decode with quicktime for every file that isnt 4:3 or 16:9.

Does anyone know what I'm on about??!!

[major]

When you add manual letterboxing, you must also set a smaller output size (smaller by the same amount of letterboxing pixels that you're adding).

[csdesigns]

OK, obviously I misunderstood what your last question was.

About QT, no, all you have to do to open a .mpv in QT is change the extension to .m2v, or force the .mpv to open in QT with the "Open with..." Finder command.

Back to your movie, are you sure it is 2.35:1, because 640x256 is actually 2.53:1. If it is definitely 2.35:1, then that means it must be 640x272, in which case for the letterboxing values, all you would have to do is set it to 78, 78, 0, 0. Your PAR should be maintained for the actual video in the resulting file, and you would just use it in DVD SP as I said previously.

BTW, this seems to only apply to AVIs. I generally encode from .MOVs, and if you use a .mov source in ffmpegX that has a wider than 16:9 PAR, even without QT decoding checked, ffmpegX automatically adds the correct sized letterboxes.

[csdesigns]

Well scratch that. Adding the letterboxing values does as you say with AVI sources. The resulting value of the MPEG-2 is 720x636 (even though QT displays it at 720x404), not DVD SP compatible. I guess one solution, is if you didn't mind converting the AVI to a intermediate QT codec, and by this I mean not just saving to a .mov wrapper, but actually encoding to a different codec. I have used wider aspect BlackMagic and MJPEG sources for MPEG-2 encoding with ffmpegX and DVD SP had no problems with them. And as I said, I didn't have to have the Decode with QT checked (I don't really know whether or not though if for .mov sources if Decode with QT is automatic).

[alph]

I hope I'm not repeating something that was said, but this is how I would have gone about it.

-Select DVD ffmpeg
-Set autosize to DVD 16:9
-Set video size to 720x336
-Set letterboxing to 72, 72, 0, 0
-No decode with quicktime (just adding this for clarity)
-Bitrate and audio options are up to you

This added letterboxing will give you a 16:9, and the a DVD player will add extra letterboxing should you play it in 4:3.

Cheers,
Alph

[csdesigns]

alph, I think your exact numbers were wrong, but it did lead me into the right direction. Scorpio, if your movie is 640x272, follow the first two steps alph mentions. Then, manually set the video size to 720x360, and letterboxing to 60, 60, 0, 0 (these are estimates are a little rough possibly, but they aren't more than a few +/- off). The rest is up to you. The resulting file will have the letterboxes, and allow you to use it with DVD SP as an anamorphic 16:9 asset, keeping the same PAR as if you had just enlarged the original source to 720x306 (2.35:1). You should be good now. Thanks for the tip alph.

[Scorpio1974]

Tried it this morning, setting video size to 720x360 with manual 60/60/0/0 and its worked a treat!

Thanks for the pointers guys...you've been a great help..

Scorpio

[alph]

n/m

[NancyS]

Video sizes are WIDTH x HEIGHT!

[mycatsnameis]

The formula works very well but I'd like to understand why. I would have though that the height and width would have to be expanded by the same proportions in order to preserve the PAR.

640 => 720 is a 1.125 ratio and
272 => 360 is a 1.32 ratio.

Why do teh proportions come out right with this approach? I would've though that using the same ratio for height and width would have been right (with straight subraction to figure out the right letter box numbers).

Also, if someone could enlighten me how to choose the rigth bitrate to max out a DVD to 4.3 gigs I would appreciate it as well. I've experimented with a few and the colour coding seems to be completely unrelated to the size of the resutling TS folder.

TIA.