What's the best way to Convert 704 to 720? Avisynth or otherwise

[VideoFanatic]

I have some 704 x 480 footage that I want to put on a BluRay disc. However BluRay only supports 720 x 480.

Could anybody please suggest the best way to do that?

I'm quite confused because when I load the 704 x 480 15 second clip in VLC Media Player with the default VLC settings it has an 8 pixel black bar on the left and right of the video (total 16 pixels). So it seems that it's adding the extra pixels to give 720. The aspect ratio is on default. If I change to 4:3 it then removes the bars and streches the image over where the bars were.


However if I load the original 1 hour video in VLC and go to the section that had the same 15 second clip, VLC now has no black bars by default. If I select 4:3 in VLC I then get black bars on the top and bottom! However when playing either video in VideoRedo I don't have any bars.

I need to know for sure what the video actually looks like - does it really have the black bars on the left or right or not? Until I know that, I can't convert to 720.

In VideoRedo I convert from 704 x 480 to 720 x 480. I load the video in VideoRedo and the video has no black bars. I then played the video in VLC and it only had a black bar above the video. Again if I switch to 4:3 in VLC, the bar is removed and the image is stretched over the bar.

This is driving me nuts! When converting from 704 to 720 should the video fill the picture or should I have a 704 picture + 16 pixels of black bars on the left & right to give a total picture of 720?

What's the best program to use for that?

I tried DVDPatcher to patch the whole file to 720. If I load the file in VideoRedo, it is indeed 720 (it has a large green border on the right side) however the file would not play on a BluRay player. So I then cropped that video in VideoRedo to replace the green bar with a black bar. To do that I cropped the right by 16 pixels which simply streches the image over the green bar. Then to keep the proportions correct, I cropped the left by -16. So basically instead of a green bar on the right, I now have a black bar on the left. That file then plays in BluRay players. I like this method because it's hassle free and I don't need to set a bitrate - it just uses the same bitrate as before. That's because DVDPatcher didnt add any data and VideoRedo is simply just swapping the borders around. Do you guys think this method is OK and won't give me any problems down the line?

Also I was just wondering, what difference does it make if I set the header bitrate in DVDPatcher to anything other than the existing bitrate of the header of the video?

I tried using HC Encoder with AviSynth. This is the script I used:

DirectshowSource("I:\New\RAW June 30 1997 Edited.mpg")
AddBorders(8, 0, 8, 0)

That converted a 704 file to 720 with black borders. However I don't like the fact that I have to mess around with bitrates, I don't have confidence in whether it's giving me as close to the original quality or not.

[jman98]

DVD supports 704, so no change is necessary if you could live with DVD. You do realize that 704/720x480 is NTSC, right? You live in the UK - I have to ask.

What's more important to you?
1) You don't care if you have to re-encode this video because it MUST be on BluRay.
- or -
2) You would prefer to keep the highest quality possible and you're willing to put it on DVD instead of BluRay if that's what it takes to preserve the quality.

[VideoFanatic]

Thanks, I know what format it is but I was just wondering what would be the best method to convert to 720 so I could have it on BluRay. So option 1.

[jman98]

Your method of adding borders is fine. If you use a Constant Quantizer in the HCenc encode you should be able to get quality extremely close to the original, but as I do not do CQ encodes and instead encode to specific bit rates, I have no personal experience to share on this. Perhaps someone else can add some pointers for you or you can look up what you need to do now that you have the name of it.

You could also resize up to 720 but I don't recommend this over just adding the borders.

[Cornucopia]

You sound confused because of the things happening in VLC. To clear this up, first find out exactly what is really stored in the file. I'd use: Gspot, MediaInfo, VideoInspector, MPEG Validator, MPEG Properties, or even AVISynth (using Info filter). BTW, these OUGHT to give you matching info.

Assuming it ACTUALLY IS 704, what's going on in VLC is just that you've got the video & you also have the "window" it's being presented in. Changing the AR like you did can change the window, not just the video, so that adds a layer of complexity.

You won't get anywhere trying to patch the file's headers: this will get you in trouble when it comes to how hardware players act on something that isn't what they're expecting.

I also recommend padding vs. stretching - less softening. I also encode to specific bitrates, so can't help with CQ either...

Yeah, it really irks me that Blu-Ray consortium chose to remove backward compatibility with VCD, 1/2D1, and D1, especially when there's LOADS of existing material out there and keeping it would have cost very little.

Scott

[usually_quiet]

ATSC SD digital over-the-air broadcast TV currently uses 704 x 480 resolution. I don't know what SD DVB-T uses for its horizontal resolution. It is kind of silly not to include exiting TV resolutions into the BD spec.

[edDV]

A correct conversion 704x480 to 720x480 would include the 8 pixel side bars. A horizontal "stretch" results in incorrect aspect ratio. Both 704x480 and 720x480 have the same 0.9091 pixel aspect ratio spec.