How to create an MPEG1 file for playback on RiVA on the Amiga

Our Amiga's are great, but they don't quite have the horsepower to decompress an MP4 file and play it back in any kind of reasonable frame rate. But... They can handle the ancient MPEG1 format pretty well with RiVA software. So how does one convert a big, flashy 4K MP4 file to a sad and pathetic 160 x 120 MPEG file to play back as a tiny thumbnail on our beloved Amiga? FFMPEG of course! I tried a ton of utilities to do this, but none worked even close to as nicely as the FFMPEG utility.

If you are afraid of the Command Prompt, this may be difficult. But it is really not too hard.

I will assume your working directory for videos is C:\VIDEO and your MP4 file is blorb.mp4

1. Open a command prompt as an administrator.
2. Type CD C:\FFMPEG\BIN and then enter.
3. Type this FFMPEG command:
     ffmpeg -i "C:\VIDEO\BLOB.MP4" -strict experimental -f mpeg -map_chapters -1 -map 0:0 -map 0:1 -sn -c:a:0 mp2 -b:a:0 32k -ar:a:0 16000 -ac:a:0 1 -c:v:0 mpeg1video -r 24 -b:v:0 512k -mbd:v:0 rd -mbcmp:v:0 rd -cmp:v:0 rd -precmp:v:0 rd -subcmp:v:0 rd -trellis:v:0 1 -filter:v:0 scale=160:120 -y "C:\video\blorb.mpg"

And what does this command do?
     a.  "-strict experimental -f mpeg -map_chapters -1 -map 0:0 -map 0:1 -sn -c" This sets the stage for the type of file we are converting from.
     b. "a:0 mp2 -b:a:0 32k -ar:a:0 16000" - This is the audio conversion. I like to make the audio 32kbs and the frequency 16000 Khz. This still sounds OK for things like spoken words. You can increase these numbers, but the Amiga will have choppier audio.
     c. "v:0 mpeg1video -r 24 -b:v:0 512k -mbd:v:0 rd -mbcmp:v:0 rd -cmp:v:0 rd -precmp:v:0 rd -subcmp:v:0 rd -trellis:v:0 1 -filter:v:0 scale=160:120 -y" - This is MPEG1 magic. 512k is the bit rate. You can make it larger or smaller, but that will affect either speed or quality of the video. 384k - 512k is usable. Too much bigger slows things down a lot. Then we have some filtering to make things pretty. And 160:120 is the size of the video. You can make it bigger or smaller.

4. The resulting video file will be an MPEG1 that should play back OK on your Amiga. Take a look at Episode 2 of "10 Minute Amiga Retro Cast" for advice on setting up and using RiVA.

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