[MEncoder-users] OCD formatting of DVDs for iPhone

[James Hastings-Trew]

Peter Sebastian Masny wrote:
> Hi all,
>
> [[[[in short, take 16:9 input and make the video 480x270, then add black 
> bars above and below to real resolution 480x320, with a 1:1 pixel ratio]]]]
>
> Longer:
> I got a command line that does a good job of converting a DVD folder 
> into an MPEG4 for my iPhone. The only problem is the aspect ratio. The 
> situation:
> 1. my movies are all 16:9 (1.77:1)
> 2. mencoder rarely accurately detects the original aspect ratio (I seem 
> to get 2.37:1 all the time)
> 3. iPhone display is 480x320 (1.5:1)
> 4. quicktime and iPhone need 1:1 pixel sizes, but iPhone will resize the 
> pixel ratio (that's the weird part)
>
> I can run dsize=480:270  and get a nice video, playable on my iPhone, 
> but when played it gets stretched to fill the screen (480x320)
>
> This bothers my OCD tendencies.
>
> I've tried to force the iPhone to add black bars to the top and bottom by
> dsize=480:270,expand=480:320, but this makes SAR 32/27 and does not add 
> real black bars.
> What's the correct incantation to in short, take 16:9 input and make the 
> video 480x270, then add black bars above and below to 480x320, with a 
> 1:1 pixel ratio?
>   
Expand, then dsize. when the dsize matches the pixel size of the frame, 
then the SAR is 1/1.

BUT, you don't need to add the black bars at all. the iPhone supports a 
480:270 size video just fine. Just make sure the dsize is the same as 
scale size. 480:320 is it's "4:3" resolution, and 480:270 is it's "16:9" 
resolution.

As for mencoder detecting the aspect ratio properly, DVDs only have two 
aspect ratios - full screen (4:3) or wide (16:9). Anything wider than 
16:9 is encoded at the 16:9 aspect, with black bars added. Further 
complicating the issue, some lower quality DVDs have "wide screen" 
movies encoded in a 4:3 frame with black bars added. However, all DVDs 
have the same size frame - 720x480 (or 720 x 576 for PAL). You can 
ignore input aspect ratio altogether by specifying your crop, scale, and 
dsize parameters and mencoder will spit out whatever you want.