I want to encode multiple aspect ratios with a zoom and downscale to 720p

[oddball]

I want to encode a bluray that has a switch from 1.66:1 ratio to 2.35:1 ratio. The bluray puts black bars on all sides for the first portion then switches to scope ratio to fill out the sides.

What I want to do is make a 720p encode whereby the first portion is zoomed out so there are NO black bars top and bottom and smaller black bars encoded on the sides then have the scope ratio portion have black bars encoded top and bottom.

From what I can gather this should be possible by editing the two files together as long as they are both exactly the same resolution?

Or is there more to it than that? Is there any way to do it in one encode?

[poisondeathray]

I want to encode a bluray that has a switch from 1.66:1 ratio to 2.35:1 ratio. The bluray puts black bars on all sides for the first portion then switches to scope ratio to fill out the sides.

What I want to do is make a 720p encode whereby the first portion is zoomed out so there are NO black bars top and bottom and smaller black bars encoded on the sides then have the scope ratio portion have black bars encoded top and bottom.

From what I can gather this should be possible by editing the two files together as long as they are both exactly the same resolution?

Or is there more to it than that? Is there any way to do it in one encode?


Unless I'm misunderstanding you, you just encode it as 1280x720.

The blu-ray doesn't put the bars, YOU put the bars on.

You pillarbox the 1.66:1 content , letterbox the 2.35.1 content

[Sharc]

..... The bluray puts black bars on all sides for the first portion then switches to scope ratio to fill out the sides....
Is your source from a blu-ray commercial disc i.e. is the format blu-ray compliant? If so, then it has the borders already applied, and you only have to resize the source (including the borders) to 1280 x 720 and encode.

Otherwise as poisondeathray suggests:
for the 1.667 content:
- resize to 1200x720
- add borders: 40 left and 40 right

and for the 2.35 content:
- resize to 1280 x 544
- add borders: 88 top and 88 bottom

Now both parts are 1280 x 720 (same resolution) which you can encode separately and then join & author with tsmuxer for example.

[oddball]

Is your source from a blu-ray commercial disc i.e. is the format blu-ray compliant? If so, then it has the borders already applied, and you only have to resize the source (including the borders) to 1280 x 720 and encode.

Otherwise as poisondeathray suggests:
for the 1.667 content:
- resize to 1200x720
- add borders: 40 left and 40 right

and for the 2.35 content:
- resize to 1280 x 544
- add borders: 88 top and 88 bottom

Now both parts are 1280 x 720 (same resolution) which you can encode separately and then join & author with tsmuxer for example.

That's what I thought. Will give it a go. Thx.

[movmasty]

Is your source from a blu-ray commercial disc i.e. is the format blu-ray compliant? If so, then it has the borders already applied, and you only have to resize the source (including the borders) to 1280 x 720 and encode.
Otherwise as poisondeathray suggests:
for the 1.667 content:
- resize to 1200x720
- add borders: 40 left and 40 right

and for the 2.35 content:
- resize to 1280 x 544
- add borders: 88 top and 88 bottom

Now both parts are 1280 x 720 (same resolution) which you can encode separately and then join & author with tsmuxer for example.
None of those borders is a multiple of 16, and this will give artifacts,
a little cropping will resolve the problem,
generally frames at 1.66 waste space on top mostly, and at the bottom,
and 2.35 at the sides.
Supposing that the originals are 1800x1080 and 1920x816,
crop to 1800x1040(i suggest 4down 36up) and 1866x816
resize to 1248x720 and 1280 x 560
And then letterbox

[paradoxical]

None of those borders is a multiple of 16, and this will give artifacts,

Why would one get artifacts by the borders not being mod 16?

[Sharc]

None of those borders is a multiple of 16, and this will give artifacts,....

Really? Yes for mpeg-2 encoding, but for h.264 / x264 I thought mod16 this is no longer an issue at all.
Am I mistaken?

[paradoxical]

Really? Yes for mpeg-2 encoding, but for h.264 / x264 I thought mod16 this is no longer an issue at all.
Am I mistaken?

Why would you get artifacts with mpeg-2? I've seen stuff padded with non-mod16 borders on mpeg-2 encodes and they had no artifacts due to that. The whole mod16 thing has been woefully overblown.

[Sharc]

Why would you get artifacts with mpeg-2? I've seen stuff padded with non-mod16 borders on mpeg-2 encodes and they had no artifacts due to that. The whole mod16 thing has been woefully overblown.
Due to the 16x16 macroblock limitations of mpeg-2. Sharp transitions within a macroblock are bitrate hungry, and if the bitrate is not available it causes ringing or unsharp / ugly transitions.

[paradoxical]

Due to the 16x16 macroblock limitations of mpeg-2. Sharp transitions within a macroblock are bitrate hungry, and if the bitrate is not available it causes ringing or unsharp / ugly transitions.

As I said, I have plenty of MPEG-2 encodes with non-mod16 borders and they have no artifacts due to that. Yes, it means that compression efficiency will be hurt, but it does not mean you will automatically get artifacts due to this. Again, the issue is woefully overblown.

[movmasty]

Maybe is overblown,
but anyway you will get smaller borders :D

[paradoxical]

Maybe is overblown,
but anyway you will get smalle borders :D

There is no maybe. I just checked a 2.8 mbit (hardly high bitrate), 720x576 MPEG-2 sample with mod8 borders and it had no visible ringing around the edges of the borders even at 4x zoom.

[Sharc]

As I said, I have plenty of MPEG-2 encodes with non-mod16 borders and they have no artifacts due to that. Yes, it means that compression efficiency will be hurt, but it does not mean you will automatically get artifacts due to this. Again, the issue is woefully overblown.
Well, if your bitrate (filesize) is limited it is wiser to spend the available bits for a better picture quality rather than wasting the bits for encoding sharp transitions between the black border and the active picture. So yes, the transitions may look nice but these bits are missing in the useful picture where you get more encoding artefacts ;).
This effect becomes of course more pronounced for high compression (low average bitrates).

[paradoxical]

Well, if your bitrate (filesize) is limited it is wiser to spend the available bits for a better picture quality rather than wasting the bits for encoding sharp transitions between the black border and the active picture. So yes, the transitions may look nice but these bits are missing in the useful picture where you get more encoding artefacts ;).
This effect becomes of course more pronounced for high compression (low average bitrates).

The compression efficiency loss is a couple of percent at worse (IIRC from some tests someone did years ago that even going mod2 had only about ~4% max efficiency loss for XviD). Even at 1 mbit your talking about 10s of kbit. That's going to make an insignificant difference if the picture is already overly compressed. Non-mod16 borders will make an insignificant difference to the video quality.

[Sharc]

The compression efficiency loss is a couple of percent at worse (IIRC from some tests someone did years ago that even going mod2 had only about ~4% max efficiency loss for XviD). Even at 1 mbit your talking about 10s of kbit. That's going to make an insignificant difference if the picture is already overly compressed. Non-mod16 borders will make an insignificant difference to the video quality.
XviD is not mpeg-2, is it?
mod16 for mpeg-2 and mpeg-4 has been discussed to death in this forum. To each his own ....

[paradoxical]

XviD is not mpeg-2, is it?

No, I didn't say it was. The efficiency loss for mpeg-2 is going to be only slightly worse at the very max. Mod8 borders (which was what was suggested) is going to effect efficiency for MPEG-2 by about 1 to 2% at worse. So that's about 10-20kbit per every mbit. If such a difference is actually enough to make noticeable effects on video quality it means you're bitrate is waaay too low.

mod16 for mpeg-2 and mpeg-4 has been discussed to death in this forum. To each his own ....

Yes, and in actual tests the bitrate difference is tiny and the visual impact is next to imperceptible. With H.264 the difference in efficiency is even tinier.