Codec for G3-Macs

[roliff]

Hi there,

during the last year I have converted all my DVD's to MPEG4-Files on my Mac G4-400 which I also use as a fileserver in my home-network.

Unfortunately it is not possible to watch the films on the older G3 Clients (iMac G3-300 and iBook G3-600). This is not a problem of the Network. I use a Gigabit backbone which provides about 400 MBit to the clients. I assume it's the codec. Even if I copy a file to the clients HD the film is not running without long stops. So it seems to me that the G3 processor is just too slow to decode.

A couple of days ago I received a film which was encoded with the following codec:

• Stream: MyFilm.mpg
  Type: MPEG program stream
  
  Duration: 1:47:29
  Data Volume: 859.00 MB
  Bit Rate: 1.12 Mbps
  
  Video Tracks:
  224 MPEG-1, 352 × 288, 25 fps, 104.86 Mbps
  
  Audio Tracks:
  192 MP2 stereo, 44.1 kHz, 128 kbps
  
  Stream Files:
  MyFilm.mpg (859.00 MB)

This file runs perfectly on all machines - even over the network - but it is not possible to convert my MPEG4 Files to this format (I use ffmpegX and Handbrake).

Which codec can I use to convert the MPEG4-files to a format that is running on the old G3 machines? The format should support the "cinemascope" format of most of the films. I don't care much for the quality as I own all the DVD's. So if I like to watch the films on a videobeamer in a couple of years I can use the DVD's.

[aedipuss]

choose a format like mpeg-2 that is easy to decode and plays fine on just about anything built in the last 10 years. mpeg-2 720x480 or 720x576 is standard dvd so both 16/9 and 4:3 are supported.

the myfilm.mpg is a vcd type video. not very good with motion but easy to decode.

[terryj]

My guess is is this film is an Mpeg-1 file?
an Mpeg-1 file should play fine on G3 hardware.

To encode into Mpeg-1, any program that can make
VCD/SVCD format discs, will do the encoding for you.
You just extract the .DAT file which is the actual MPEG-1
from the disc, and transfer that to your clients/server.

[ffooky]

I've found that G3 6OOMHz iMacs can handle generic MPEG-4 (XviD etc) files as long as the total bitrate is below about 950kbps. I do have a 400MHz model but I haven't discovered the cut off point for that yet. I'd recommend experimenting with conversions at varying bitrates to XviD with ffmpegX...even at a relatively low rate it *should* give better results than MPEG-1.

You can pretty much forget MPEG-2. A 400MHz G3 can handle the same file just dandy as long as it's presented as a VOB in a VIDEO_TS folder but unwrapped ?...you'll get about one frame in a thousand.

I've never been able to find out why this is. Is it because in one form it's decoded by hardware and the other by software ?

[dnix71]

I used to have a bondi G3. It wouldn't play mp4 video without a lot of dropped frames. The bus was only 33 MHz.

MP4 might be doable on a 400 MHz dv iMac (the lavender colored ones). They used pc100 memory and had 66 MHz busses.

Whatever Quicktime was using under OS 9 would be the best choice, if you still have the original software and the time to convert.

I gave up on older macs. Here is a blue and white on ebay going for less than $100.
http://cgi.ebay.com/Apple-Power-Mac-G3-350MHz-256MB-10GB-CD-OS-X-10-4-Tiger_W0QQitemZ1...QQcmdZViewItem

and an 800 MHz G3 for $140 http://cgi.ebay.com/Apple-eMac-800-mhz-256-ram-40g-hd-cd-Tiger-OS-X_W0QQitemZ330171117...QQcmdZViewItem

[tomlee59]

First, I'll assume that you meant actually meant a video bitrate of 1.0486Mb/s or something like that, rather than 100x this rate.

In any case, the file you've described is an XVCD in PAL. As you've found, it is (and should be) readily playable on your imac. I can play files like this -- fullscreen -- on a pre-G3 Powerbook 3400c, thanks to mpeg1's light decode requirements. Aedipuss's suggestion of encoding into mpeg2 is not a good one for the imac. Mpeg2 is too processor-intensive. And since you stated that hi-def quality is not an end goal, stay with mpeg1 at 352x288 (the standard PAL VCD framesize).

To produce such a file using a mac, you can use ffmpegx, among other tools. It will happily convert from MP4 into XVCD (use the KVCD preset). Just unclick "author" and it will stop after it's produced an mpeg-1 file that will be playable on computers of (nearly) any platform.

For widescreen content, you may have to click (or unclick) the "letterbox" option. The correct setting depends on whether the source is letterboxed or not (ffmpegx is not quite smart enough to figure out the correct setting on its own). If in doubt, encode for a short time, look at the result, and either continue or restart, as necessary.