How can I change the aspect ratio of an MPEG-2 video into 2.35:1?

[ryanfever]

Hello.

I captured a movie which was aired in the aspect ratio 16:9, but letterboxed, so the video's aspect ratio is 4:3. Here comes the trouble, the movie's original aspect ratio is 2.35:1 (Cinemascope). The broadcasting station stretched it to 16:9.

In the end, I'd like to have a DVD with the movie in the aspect ratio 2.35:1. It would be terrific if there is a possibilty to create an anamorphic DVD (like shown here).

I demuxed the MPG file and now have an M2V file and an MPA file. Now, I want to use TMPGEnc Plus in order to cut the unwanted video material at the beginning and the end, and cut off the black bars. Both, I can easily do with the source range option and the clip frame option. Unfortunately, TMPGEnc Plus doesn't offer the possibility to change the aspect ratio into 2.35:1 by "squishing" the image.

How can I do that? And is it possible to create an anamorphic DVD as I explained above?

[Cornucopia]

Yes, it's possible but not quite as you explained.

You need to fiddle with the "source pixel aspect ratio".

Make sure you don't crop ALL of the black bars. DVDs only support 16:9 and 4:3, so if you have a 2.35:1 image, it needs to have the extra letterboxing to at least fill out to 16:9.

Scott

[minidv2dvd]

the 2.35:1 movie was most likely panned and scanned to 16/9. the rest is gone for good. highly unlikely they broadcast it horizontally squished, as every viewer would have complained. best bet would be to rent the movie if you want the original format.

[ryanfever]

Make sure you don't crop ALL of the black bars. DVDs only support 16:9 and 4:3, so if you have a 2.35:1 image, it needs to have the extra letterboxing to at least fill out to 16:9.

I am not sure if you understand what is the case. When I crop the the black bars, it then is 16:9 as the movie was aired letterboxed (16:9 in a 4:3 image). And I definitely don't want any black bars in the image. I want to horizontally squish the 16:9 image to 2.35:1 or create an anamorphic DVD, so it is displayed correctly both on a standard full screen TV and on a widescreen TV (16:9).

the 2.35:1 movie was most likely panned and scanned to 16/9. the rest is gone for good. highly unlikely they broadcast it horizontally squished, as every viewer would have complained.

The image is definitely horizontally squished. I can determine that by lookin at the heads of people in the movie. The movie wasn't aired with a cropped image.

best bet would be to rent the movie if you want the original format.

Not possible because it is an old movie which wasn't ever sold on DVD. If there would be an easy way to get the movie, I wouldn't have to grapple with this matter.

[minidv2dvd]

can you post a small sample somewhere please? it's much easier to work out a solution that way. but a best guess would be a 2 step process, cropping off the black bars and encoding to huffyuv lossless square pixel 2.35/1 and then re-encoding back to mpeg-2.

[FulciLives]

Load the video into VirtualDub or VirtualDubMod and take a snap shot. This will give us an exact frame as it is encoded. Do not resize it at all. Just post it here. Make sure you use the built-in snap shot tool ... don't just do a screen grab. That doesn't help much.

- John "FulciLives" Coleman

[ryanfever]

Snap shot from VirtualdubMod (This resolution isn't displayed when played with a common player.)


Snap shot from VLC media player


Heads are vertically too long (snap shot from VLC media player)

[guns1inger]

No pictures here ?

DVD doesn't support 2.35:1. It supports 4:3 and it supports 16:9. That's it. (Mpeg-2 however also supports 2.21:1 - go figure).

Is just a matter of cropping the right amount from the top and bottom of the frame, then resizing back to full resolution, then re-encoding. It has been covered many times before. For NTSC it is 60 from the top and 60 from the bottom, the resize back to 480. For PAL it is 86 from the top and bottom. (Note assumes the letterboxed video is 1.778 or wider. For 1.66 it is more complex).

[poisondeathray]

I don't deal much with DVD anymore (or PAL for that matter) so I'm not sure if this is correct or legal for PAL, but I'll take stab

Your active image area is ~542x426 as determined from the 1:1 image from vdubmod. A 16:9 PAL DVD displays as 1024x576, So working backwards 1024/2.35 ~ 430 vertical pixels. I would use 432 for mod16, but it's not necessary. So borders would be (576 - 432)/2 = 72 top and bottom. I assume you want to crop off the logo and replace with "normal" black borders

MPEG2Source("file.d2v")
Crop(0,78,-2,-72)
LanczosResize(720,432)
AddBorders(0,72,0,72)

This will give you an active image area of 1024x432 ~2.38 DAR, you can adjust it a bit if you want a slightly different ratio

Here is the "PAL MPEG2" sample of the image (I just made a 1 sec clip "1.m2v" which you can download to check), and the screenshot of how it displays with MPC (it might not display right in the browser - its too wide - so you might have to save to desktop)

1.m2v

[FulciLives]

I came up with 80 off the top and 74 off the bottom then 2 from the left and 4 from the right.

So I guess I would put 76 on the top and 78 on the bottom when adding it back and as for the pixels from the side ... I probably wouldn't care and just resize to 720 but since this is a TV capture it might be better to go 704 so ... my version would look like this:

MPEG2Source("file.d2v")
Crop(-2,-80,-4,-74)
LanczosResize(704,422)
AddBorders(8,76,8,78)

That's how I would do it

OR ... you could just resize to 720x576 (without any cropping) and leave it at that ... but that's too simple LOL

- John "FulciLives" Coleman

[ryanfever]

Thanks for your efforts.

Did you use VirtualdubMod for all that?

This code you included is for AviSynth, right? I am not familiar with AviSynth, so how do I use this with either VirtualDubMod or TMPGEnc Plus?

[poisondeathray]

Hi there, you can use vdubmod for all that (or vdub with the mpeg2 plugin), they have all the crop, resize and addborders (I think) , but as soon as you use a filter in full processing mode a colorspace conversion from YV12=>RGB is done and you lose quality upon converting it back to YV12. If you use an avisynth script, you avoid all that if you use "fast recompress mode" . TMPGenc also does an internal colorspace conversion IIRC

Also if your goal is DVD, it doesn't entirely make sense to use vdub family, because they cant output MPEG2. You could use avidemux which looks like vdub, but has more support for other formats. You would just use the corresponding commands like crop, add borders in the filters, then encode to MPEG2 , then author.

If you want better quality I would use avisynth + good encoder like CCE (not free) or HCenc (free), then author with an authoring program. Avidemux's MPEG2 encoder is based on ffmpeg and is fairly good, but CCE and HCenc are usually regarded as better

[ryanfever]

MPEG2Source("file.d2v")
Crop(0,78,-2,-72)
LanczosResize(720,432)
AddBorders(0,72,0,72)

Is this really everything AviSynth needs? I have an M2V file. This works too, right?

Can I add an option to chose a source range? I'd like to cut the previous and subsequent images which aren't related to the movie.

[poisondeathray]

If you're not familiar with avisynth to might be easier to use avidemux, or even vdub (output to a lossless intermediate or frameserve) then input that into an mpeg2 encoder


But yes, you can choose a range, you would use trim()

For example, Trim(0,100)++Trim(200,300) would return frames 0-100 and 200-300, leaving 101-199 cut out

You would index your file with DGIndex, and write the script. There is a 1page quickstart manual that comes with DGIndex and explains how to do this. To join audio & video, you would use audiodub(video,audio), and don't forget to enter the audio delay, as written in the demuxed audio name in ms (in this fake example there was a 150ms so I entered 0.150). You can use a visual script editor like avsp to find the cutsite frame numbers. e.g.

LoadPlugin("C:\PATH\DGDecode.dll")
MPEG2Source("file.d2v")
Crop(0,78,-2,-72)
LanczosResize(720,432)
AddBorders(0,72,0,72)
vid=last
aud=NicAC3Source("file.ac3").DelayAudio(0.150)
AudioDub(vid,aud)

Trim(0,100)++Trim(200,300)

You can preview the script in MPC, to make sure it's correct and in sync

[ryanfever]

I think I understand all that. But i have an MP2 audio file. What do I use instead that line with AC3... ?

[poisondeathray]

I think I understand all that. But i have an MP2 audio file. What do I use instead that line with AC3... ?

That's great! I struggled with avisynth at first (and still do with many complex functions), but there's so much to learn but it's very powerful and I can't believe I didn't learn the basics sooner!

You would use the same .dll , nicaudio.dll which you put into your avisynth plugins directory

NicMPG123Source("audio.mp2")

[ryanfever]

All right. I don't need the trim option anymore, as DGIndex did that already. Here's what I now have:

LoadPlugin("<path to DGDecode.dll>")

MPEG2Source("<path to D2V file>")
Crop(2,80,-4,-74)
LanczosResize(720,432)
AddBorders(0,72,0,72)
vid=last
aud=NicMPG123Source("<path to MP2 file>").DelayAudio(0.031)
AudioDub(vid,aud)

Some last questions:

I want to have an M2V file and an MP2 file (both I now have, plus the D2V file) as the output. Do I just leave out AudioDub(vid,aud)?

I changed the crop parameters - compared to your suggestion - because I want to crop the black areas on the left and right side and a little more on the top an bottom. Do I have to change the other parameters as well? (If this makes it more complex, a tiny unnotable change of the image is no problem.)

How do I start the AviSynth script?

[poisondeathray]

The script is just a set of instructions. So you would open it with an encoder e.g. HCenc, and it feeds the encoder frames as specified by your script. You then set your encoding settings (don't forget 16:9 flag for your particular example) and presto it will give you a new .m2v file which you can use in a DVD authoring program. Similarly the script would be fed into an audio encoder (that accepts avs scripts) for mp2 or ac3. An example would be behappy or megui. If your audio already matches, and no cutting is required, then you don't need to re-encode it.

Assuming you are cutting out commercials, that sort of thing, with Trim() you have to keep the AudioDub(), or the video won't match the audio (they will end up different lengths). This way, both audio & video are in sync, and cut at the same points. Even if you don't use Trim() anymore, you can use it to check to see if sync issues exist. If the audio & video already match up, you can also do it separately (separate script for audio and video without audiodub). If you need just the video, you don't need anything below the addborders line

The reason you should prefer using a script for audio (if you are encoding audio) is that if you input audio directly instead of using an .avs, it often goes through your directshow subsystem and can get mixed or filtered, if you're are not careful about your filter chain

You can visually preview the script in avsp (push f5), and adjust the crop values as you see fit, but the final PAL dimensions have to be 720x576, so I think your adjusted script looks fine. Also playback the script in MPC to double check the sync and cutsites are indeed correct

[ryanfever]

I used the AviSynth script and HCenc. It worked well. I now have a video with an aspect ratio of 16:9, but the movie is 2.35:1.

Thanks for your help.

[FulciLives]

Glad it worked out for you ryanfever and kudos to poisondeathray on an excellent job with the directions etc.

Sorry I missed it all but I was sleeping heh

- John "FulciLives" Coleman

[Cornucopia]

...It worked well. I now have a video with an aspect ratio of 16:9, but the movie is 2.35:1.

Thanks for your help.

Even though you said this...

...I am not sure if you understand what is the case.

of what I said...

Make sure you don't crop ALL of the black bars. DVDs only support 16:9 and 4:3, so if you have a 2.35:1 image, it needs to have the extra letterboxing to at least fill out to 16:9.

That is the same thing in the end.

Scott

Glad it finally worked out for you, anyway.

[dj_osiris]

Stumbled upon this thread while doing a search, great stuff here. This is an example of why I love the boards here.