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Divx Encoding on a Mac

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Conrad Olson
Divx Encoding on a Mac
on Apr 7, 2008 at 12:20:55 pm

Hi Guys,

I'm not very familiar with the Divx format. We usually deliver WMV or QuickTime files to our clients but for this particular project we've been asked for Divx files that will be played on some kind of LCD screen with in-built decoder (like a photo frame).

I have two questions;

1. Is there any pro level Divx encoder on the Mac?
2. Is there a way of encoding a CBR (constant bit rate) Divx file?

Someone in my office had encoded a test Divx file from After Effects on a PC using the codec from divx.com. It was 8.9MB and looked great. I've spoken to him and he didn't change much from the default settings. I can't get back to that PC so need to try and encode them on the Mac and I'm struggling to replicate the quality of the encode at the same file size.

I downloaded the Mac Divx codec from divx.com and used MPEG Streamclip for the first attempt. These looked fine but were too big, when I tried to lower the bit rate to match the file size of the test encode there was a big quality hit. I think there is a conflict between the settings in the Divx window and the MPEG Streamclip settings.

My next attempt was with the Divx Converter from http://www.divx.com. I thought this had cracked it. The files looked as good as the test and were the same size but when we sent them off to the client they said that the peak bit-rates were too high to play on these screens that they have.

I thought I'd encoded them CBR (the bitrate in QuickTime didn't change as I played the file) but when I checked them in VLC I saw that they were VBR and the peak rates went as high as 6,000kbps when the average bit rate I'd set was 807kbps. In VLC the test file only went over 2,000kbps a couple of times but the average bit-rate was higher. I can't see a CBR option anywhere in the Divx Converter or anywhere to limit the max bit rate during the VBR encode.

I have also tried ffmpegX but I'm having the same problems as I did with MPEG Streamclip and I can't see a CBR option there either.

I'm I missing a setting somewhere or is this it for Divx encoding on a Mac? I feel like there should be more pro-level options but the only packages that I can find are either Freeware or $10.


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Daniel Low
Re: Divx Encoding on a Mac
on Apr 8, 2008 at 2:59:25 pm

As the Divx CODEC is Quicktime based, any application working in Quicktime will be able to access the CODEC.
Your best bet is to use a dedicated and professionally supported transcoding application like Episode. This sort of application will provide proper bitrate control as well as many other tools to get the best looking output at the desired bitrate.
You can download a trail of Episode from http://www.flip4mac.com.

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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Conrad Olson
Re: Divx Encoding on a Mac
on Apr 8, 2008 at 5:08:01 pm

Hi Daniel,

Well after two days of messing around with the DivX Converter, ffmpegX, MPEG Steamclip etc. I tried the trial of Episode. To start with it didn't seem to have the options I needed but then I saw the VBV setting. According to the Episode manual it seems that even when you set an encoder to encode something at CBR the bit rate will still vary but as long as the rate over 5 seconds averages to your target then it counts as CBR. This VBV setting allowed me to change the time over which it averages the bitrate and by setting it to zero the bit rate varies much less so I get rid of the big peaks.

I'm surprised that I couldn't find that setting in any of the other applications. Maybe if I'd learnt how to use mencoder from the command line I could have figured it out. I'm gad I had an reason to convince my boss to get Episode though. It seems like a pretty cool app.

I do have one question. I'm encoding these files using one of the MPEG4 templates. There doesn't seem to be a Divx or Xvid option in Episode. Is it possible? And what are the differences between Xvid and MPEG4?



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Daniel Low
Re: Divx Encoding on a Mac
on Apr 8, 2008 at 6:53:11 pm

Episode is the best transcoder on the Mac and one of the better ones out there on any platform. Indeed CBR does not mean 'flat' but a constant average over a set period of time.

Divx is based on MPEG-4 advanced simple profile but is not MPEG-4 standards compliant. By all means start with an MPEG-4 template, and adjust it, accessing Divx by choosing to output to MOV with the video encoded as Quicktime (audio as MP3) and then under the video tab choose divx from the drop down of codecs.

Xvid is free
Divx is not


__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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