AVCHD to DVD: aspect ratio problem

[The Realms of Gold]

Dear all,

I'm having difficulty preserving proper aspect ratio when burning AVCHD files to DVD. I've read up on this quite a bit, and it seems that AVCHD's native aspect ratio is 4:3 and that often players automatically stretch their output image to compensate. The video I'm shooting, on a Canon Vixia HF-M300 in "XP Mode," is 1440x1080, in 4:3 pixel aspect ratio. When it plays back, its actual ratio, with square pixels, is 1.78:1.

When I burn one of these videos to DVD, it comes out vertically stretched. I'm looking to better understand what options I have for modifying the aspect ratio for a DVD. I read on this forum that this specification, at least in H.264, can be written into the file header, but the best way to ensure all players will display the video properly is to modify it manually.

When I go to use HandBrake to convert my .MTS files into H.264 or even into part 2 MPEG, the program crashes if I try to run the re-encoding process after specifying a manual aspect ratio (the option "None"). What else can I do? Any suggestions are much appreciated. Thanks!

[poisondeathray]

The PAR is 4:3 , but the DAR is 16:9

16/9 = 1440/1080 x 4/3

For SD DVD you resize to 720x480 (assuming your are in NTSC land ) and set the flag to 16/9 in the encoder . SD DVD is MPEG2 only. (Technically you would resize to 704x480 and add 8px borders left and right for perfect AR, but most people wouldn't notice the slight AR error)

For h.264 files you can either set the --sar x:y (same thing as the PAR, think of it as w:h of pixels) to encode into the stream , or set the flag in the container to 16/9 (either with mkvtoolnix for mkv container, or mp4box for mp4 container)

Another option is to resize to square pixels 1:1 e.g. 1920x1080

So 16/9 = 1920/1080 x 1/1

[The Realms of Gold]

Hi poisondeathray,

Thanks for helping me out. A few questions for you, or for anyone:

1. What do PAR and DAR stand for? Is SD-DVD's native aspect ratio 16:9?

2. What's the best way to set those flags? I've seen mkvtoolnix and mp4box recommended before, but it seems I should only use those if I'm trying to burn files that I've transcoded from the masters (which I'm using HandBrake for). I was hoping TSSniper, which I'm using to cut my masters into final scenes, or DVDFlick, which nicely burns my master MTS files to disc, would have options for specifying aspect ratios, but neither does. DVDFlick has one simple 4:3 or 16:9 selection option, which only boxes (on all four sides) the same stretched output.

3. Does anyone have any recommendations on resizing to square pixels, and is this a good way to go anyway? (I'm trying to ensure maximum compatibility, which is far more important even than quality for my purposes.) HandBrake is my favorite thing since sliced bread, but if no one knows how to stop it from crashing when resizing to 1:1 pixels, I might need a different solution.

Thanks!

[poisondeathray]

There are at least a dozen well written posts on PAR SAR DAR etc... pleasE use search.

*But to warn you they have different meanings and definitions depending on what standard you are using. MPEG2 uses different terminology than MPEG4 for the same acronym

DAR is the display aspect ratio

In mpeg4, SAR is the sample aspect ratio, is the w:h of the pixels, but in mpeg2 they call it PAR or pixel aspect ratio

EITHERWAY, the math is the same, no matter what you call it

DAR = (w:h of the frame size) x (w:h of the pixels)



SD DVD can be either 16:9 or 4:3 , but this is separate from the active content (it might be full frame, or letterboxed for example) . If it was letter boxed the actual AR would be wider than 16:9 . For example hollywood movies are often 2:35:1


If you cut with ts sniper, the flag should remain in the streams, so when the cut streams are played, they will display as 1920x1080

Only when you re-encode do you have to do something else - EITHER encode at stream level or flag at container level. For DVD you set 16:9 . For maximum compatibility of files other than DVD or blu-ray or avchd discs, you use square pixels (but it takes more bitrate). Nowadays, almost everything accepts flag signalling, expecially at the stream level. In handbrake you would use --sar 4:3 . You can use other x264 GUI's as well if handbrake is crashing e.g megui, ripbot , xvid4psp etc...

Also what your target is determines if you deinterlace or not. For progressive display like web you should probably deinterlace. For DVD, blu-ray, you would probably leave it interlaced (although DVD requires a special interlaced downscale resize)

[The Realms of Gold]

Thanks for the clarification. I believe I understand the math better now, having read your post and some others. What I can't figure out is why none of my efforts have resulted in the proper display aspect ratio, notably my attempt with MP4Box to specify a 1:1 AR.

Would someone be willing to provide me with instructions? I think I have all the concepts straight -- I just must be missing a step, or something. I'm most interested in truly understanding the process, so I want to see if I can get both methods right -- encoding a flag at the container level, and actually re-encoding the stream with square pixels.

Thanks for your patience and help!

[poisondeathray]

You probably mean 16:9 AR , with 1:1 pixels - that just means resize to 1920x1080 . Square pixels are default. No flag required. Here's the math:

16/9 = 1920/1080 x 1/1



DVD cannot use square pixels

[The Realms of Gold]

Hi all,

Having left off this project for several months, I'm back where I left off. (Thanks to poisondeathray for all the advice he's already given me!) My question now is: how do I specify the SAR as 4:3 in Handbrake? I am not using the command line, and in the GUI (Advanced tab, field at the bottom), the syntax is different than the CLI:

PARAMETER1=VALUE1:PARAMETER2=VALUE2:[...]

So specifying an SAR of 4:3 with the CLI syntax ("--sar=4:3") would result in a syntax error, because the colon would signify a new parameter. What's the correct syntax for the GUI?

[johnebadbak_70]

this tool is worth a look as i have altered aspect ratios with this tool

https://www.videohelp.com/tools/XviD4PSP