ffmpegX squeezes PAL SVCD horizontally

[havema-1]

Input: Full quality DV encoded PAL QT file exported from iMovie 2.

ffmpegX settings: SVCD (PAL) Quick Preset.

It seems that ffmpegX 0.0.6i (as well as earlier versions) squeeze PAL DV source horizontally by adding 15 black pixels to the left and right when encoding it as SVCD.

According to the following Digital Video Resolution and Aspect Ratio Conversions page there should be no such added borders when encoding DV to SVCD:

<http://www.iki.fi/znark/video/conversion/>

With a PAL/NTSC DV source a straight DV 720x576/480 to SVCD 480x576/480 scaling is needed to preserve the aspect ratio.

On the other hand, if the target resolution is CVD-like 352x576/480 or VCD-like 352x288/240, I have 1st scaled horizontally to 360, then cropped 8 pixels from the left and right to 352, which maintains the original aspect ratio (with VCD-like target I have also scaled vertically 576/480 to 288/240).

The same calculations apply also when going from MPEG back to DV although apps like DiVA seem to miss the capability to add borders which is needed to maintain the aspect ratio.

[major]

Thanks for the link. I add this in my todo list.

[havema-1]

Thanks for the reply. Where did the added borders which distort the image came from?

BTW, I just upgraded to 10.2 and unlike with older 10.1.5-compatible ffmpegX versions, now the SVCDs seem to play smoothly and without the stutter that plagued older versions on my Pioneer 444. ffmpegX interface is also considerably more Mac-like than in MediaPipe so it would be nice to have the aspect ratio conversions right.

Just to correct a slight typo in my previous post and for some background: I have preferred to encode my XSVCDs to some legal DVD resolution like (PAL/NTSC) 352x288/240, 352x576/480, 704x576/480 or 720x576/480 with 48 kHz audio (instead of SVCD 44.1 kHz) so I can later author and concatenate them to real DVDs with minimum fuss and with no need to re-encode. So:

1. To convert 720x576/480 PAL/NTSC DV to SVCD 480x576/480, I have simply scaled to 480x576/480. But SVCD resolution isn't legal on a DVD so I have used some of the following resolutions on my XSVCDs:

2. To convert 720x576/480 PAL/NTSC DV to DVD 704x576/480, I have simply cropped 8 pixels from left and right to 704x576/480.

3. To convert 720x576/480 PAL/NTSC DV to CVD/DVD 352x576/480, I have 1st scaled to 360x576/480, then cropped 4 pixels from left and right to 352x576/480. (I guess it doesn't matter if I 1st cropped 8 pixels from left and right to 704x576/480, then scaled to 352x576/480).

4. To convert 720x576/480 PAL/NTSC DV to VCD/DVD 352x288/240, I have 1st scaled to 360x288/240, then cropped 4 pixels from left and right to 352x288/240. (I guess it doesn't matter if I 1st cropped 8 pixels from left and right to 704x576/480, then scaled to 352x288/240).

5. The same calculations apply also when going backwards. For example: To convert CVD/DVD 352x576/480 to DV I have 1st added 4 pixels to left and right to 360x576/480, then scaled to 720x576/480. (I guess it doesn't matter if I 1st scaled to 704x576/480, then added added 8 pixels to left and right to 720x576/480).

With these conversions the aspect ratio is always preserved. Unfortunately apps like DiVA currently seem to miss the capability to add borders which is needed to maintain the aspect ratio when going backwards. With MediaPipe's Scaler, Crop and Add Borders pipes this is possible.

[major]

Starting from version 0.0.6L the auto-letterboxing can now be disabled.

[havema-1]

> Starting from version 0.0.6L the auto-letterboxing can now be disabled.

Thanks! Now the aspect ratio is preserved in PAL/NTSC 480x576/480 SVCD and 720x576/480 DVD with 720x576/480 input!

But if the target resolution is VCD 352x288/240 or CVD 352x576/480, the original aspect ratio is not preserved because there seems to be only a straight horizontal scaling from 720 to 352 instead of the proper scaling to 360 followed by cropping to 352 (or cropping to 704 followed by scaling to 352).

And it seems that it isn't possible to just crop 720x576/480 to 704x576/480 without adding black borders to the left and right?

Is it possible to scale & crop also 704 and 352 horizontal resolutions right in ffmegX? I know this may seem like nitpicking but it would be nice to get the aspect ratio conversions exactly right

Interlaced output is on my wishlist, too! (Or are my wishes already fulfilled in ffmpegX 0.0.6n ... I can't test ffmpegX fast enough because there seems to be a new version before I can test the previous

Keep up the good work!