Need Help... having problems converting MKV files to AVI .......

[chryslus]

Hello,guys...

I'm on a G5 (not the Intel model) and i'm experiencing some problems operating the ffmpegx.

First, when i tried to convert one MKV, i got this message

another time i imported a mkv file into the window... i heard the "ding" telling me it was finished doing its thang, but i got this instead


i'm still a novice when it comes to computers, but i know i'm not doing something right.

One final thing happened...

I imported yet another mkv file into the window and after it finished, it managed to convert the file to an AVI, BUT..... the audio was cool yet the picture was super choppy.. i mean to the point where the video would freeze for 2 seconds and then go to the next alloted frame. Like some bad stop motion picture.

So guys.. i lend my ear to your wisdom.

i've done some major research on your board and it said something about using SUPER, but it's only for Windows...

and i'm one of those Mac guys most PC users hate. Oh well, what can you do?

SO.. what should i do?

[Case]

a. Many codecs need the video size to be divisible by 16, because they describe the clip in blocks of 16x16 pixels. If you try to encode to 712x480, it won't work because 712:16=44.5, not a round number. 720x480 or 704x480 would be more likely to work. Just find a valid number close to what the desired aspect ratio suggests.

b. Sometimes QuickTime Player won't open movie files because they are the wrong file type. Or, if the conversion didn't go well, your output movie could be a zero byte file, which obviously won't play.

c. No idea on the choppy video.

[chryslus]

Well, i'm really not that great in ratio deduction.

What's the best thing to do if it is a zero byte file?

[Case]

Well, i'm really not that great in ratio deduction.

MKV files allow for some trickery with the aspect ratio, so there is a bit more to it than with your average video file. Play the file in MPlayer or VLC, look at the width and height of the video. Most common ratios are 4:3, 16:9 and 2.35:1 (examples).
When in doubt, take a screenshot and measure the width and height in pixels.

aspect ratio = width : height (e.g. 640 : 480 = 1.33 = 4:3)
width = height x aspect ratio (e.g. 640 = 480 x 1.33)
height = width : aspect rato (e.g. 352 =~ 640 : 1.78)

For a 4:3 (1.33:1) aspect ratio and a target height of 480 px, the desired width is 480x4:3=640. In that case, set the video size to 640x480.
For a 16:9 (1.78:1) aspect ratio and a target width of 640 px, the desired height is 640:1.78=360. In that case, set the video size to 640x352, as 352 is the closest valid number to 360.

Now, MKV files can have a custom aspect ratio, so you should confirm the aspect ratio in playback, not just taking it's native resolution. An MKV file may be native 720x480 and have a 4:3 aspect ratio, so the image is squeezed 89% horizontally for correct playback. To convert such a file to AVI, 640x480 may be more appropriate than 720x480, as AVI has (almost) no support for custom aspect ratio.

(One might make such an MKV file for taking unaltered broadcast resolution, preserving every detail that is received.)

What's the best thing to do if it is a zero byte file?

A zero byte output file means a fatal error in the conversion, which may be solved by looking at the log in the ffmpegX Progress window (). If you post the log here, we can have a look at it.

[tbluewater]

Use mencoder with MKVToolNix to decode the existing compression algorithm and re-encode video with a new one in a different container.