avi to mpeg adventure using ffmpeg in linux text mode

[doru001]

This is what we call TV OVERSCAN

http://en.wikipedia.org/wiki/Overscan

If you have a modern TV like some sort of flat panel LCD or Plasma etc. then you might be able to turn it off but if it is an older tube type TV or some sort of rear projection then you cannot.

Thank you for your help. The DVD player has two settings: one for TV type, another for format type. The format was set to 16:9, but the TV was set on 4:3. When I set TV to 16:9 I could see the full correct image. Apparently, while set to a 4:3 TV, the DVD player decided to crop the image on the left and right sides to help me against my will.

The command I used:

time ffmpeg -i concat:file1.avi\|file2.avi -vf scale=720:496,pad=720:576:"(out_w-in_w)/2":"(out_h-in_h)/2" -target pal-dvd -c:a ac3 -b:a 384k -aspect 16:9 file.mpg

496 is calculated this way (everything in pixels): 544/256 (original size) = 720/x (new size) => x~=482. The smallest multiple of 16 bigger than 482 is 496.
720x576 and other format parameters are defined here: http://mplayerhq.hu/DOCS/HTML/en/menc-feat-vcd-dvd.html.

A few notes on ffmpeg (the ffmpeg.org version, not libav):
- definitions of sar and dar in the manual and documentation seem to be wrong. Wikipedia is right: http://en.wikipedia.org/wiki/Pixel_aspect_ratio.
- for bit rates, 448kb is 448000 bits, because we are talking about serially transmitted data.
- -ss and -t work with seconds only, no minutes or hours.
- mplayer, the default player on Ubuntu, ceases to work after ffmpeg.org is installed (some libraries conflict). vlc is good and works.
- I have received some error messages about frames, one at the joint of the two files, several towards the end of the second file. Still, the video looks fine at its low resolution.

Thank you all, especially intracube and FulciLives.

[FulciLives]

Well FitCD can adjust itself to add extra black around the image to account for TV overscan but really, these days, that's not a good idea. Just turn it off on your TV. New TV's don't need it. They only have it for legacy purposes. For example you want it on if watching a VHS tape. If watching a Blu-Ray then you want it off.

[intracube]

Thank you for your help. The DVD player has two settings: one for TV type, another for format type. The format was set to 16:9, but the TV was set on 4:3. When I set TV to 16:9 I could see the full correct image. Apparently, while set to a 4:3 TV, the DVD player decided to crop the image on the left and right sides to help me against my will.

There's usually an option on DVD players for choosing how to view 16:9 video. The options are often labelled 'letterbox' and 'pan-scan'. It sounds like your player is set to pan-scan.

The command I used:

time ffmpeg -i concat:file1.avi\|file2.avi -vf scale=720:496,pad=720:576:"(out_w-in_w)/2":"(out_h-in_h)/2" -target pal-dvd -c:a ac3 -b:a 384k -aspect 16:9 file.mpg

496 is calculated this way (everything in pixels): 544/256 (original size) = 720/x (new size) => x~=482. The smallest multiple of 16 bigger than 482 is 496.

Ffmpeg's video filters aren't limited to mod16 values (they might need to be even numbers though). Just make sure that the video output gets scaled/padded to a mod16 resolution (720x576 in your case).

- for bit rates, 448kb is 448000 bytes, because we are talking about serially transmitted data.

You're mixing up bits and bytes there - but yes, 448kb = 448000 bits. 1kb = 1000 bits in this case. I forgot this before.

-ss and -t work with seconds only, no minutes or hours.

From the manual: position may be either in seconds or in "hh:mm:ss[.xxx]" form.

[doru001]

Ffmpeg's video filters aren't limited to mod16 values (they might need to be even numbers though). Just make sure that the video output gets scaled/padded to a mod16 resolution (720x576 in your case).

The dvd player went crazy when I used 482 instead of 496. Or maybe it was caused by that automatic cropping? No problem with ffmpeg.

You're mixing up bits and bytes there - but yes, 448kb = 448000 bits. 1kb = 1000 bits in this case. I forgot this before.

Indeed, I corrected this, thank you. Big mistake.

-ss and -t work with seconds only, no minutes or hours.

From the manual: position may be either in seconds or in "hh:mms[.xxx]" form.

Yeah, that's why it is funny that it does not work and it fails with no clear message.

[doru001]

Well FitCD can adjust itself to add extra black around the image to account for TV overscan but really, these days, that's not a good idea. Just turn it off on your TV. New TV's don't need it. They only have it for legacy purposes. For example you want it on if watching a VHS tape. If watching a Blu-Ray then you want it off.

That was no overscan problem, but a double setting in the dvd player. However, you did help me by indicating the right place to look. I was prepared to process the whole file again, with a vertical resolution increased by 16!

[intracube]

The dvd player went crazy when I used 482 instead of 496. Or maybe it was caused by that automatic cropping? No problem with ffmpeg.

I can't see why it would. As long as the video that ffmpeg outputs is 720x576 and 25fps it should be ok. Always double-check with mediainfo.

[doru001]

The dvd player went crazy when I used 482 instead of 496. Or maybe it was caused by that automatic cropping? No problem with ffmpeg.

I can't see why it would. As long as the video that ffmpeg outputs is 720x576 and 25fps it should be ok. Always double-check with mediainfo.

The dvd player was wrongly set for a 4:3 TV screen. Zoom was on 16:9 and TV zoom on Full, no problem here. The 720x482 image was shown touching the top and bottom margins (padding disappeared), with huge padding on left and right borders, cropped on left and right borders, and very distorted (compressed horizontally). That was so bad that I went to do the 720x496 format, even though this change only increased the vertical dimension, therefore presumably increasing the distortion. The 720x496 looked well, padding top and bottom, touching left and right, only that it was cropped left and right. Then I discovered the wrong 4:3 TV screen setting in the dvd player. Correcting this to 16:9 solved all issues. Now, I don't know how would have the 720x482 video looked with a correct 16:9 setting on dvd player, but I stick with the multiple of 16 vertical resolution.