[grovberg]

Just thought I would poll the group and see where most people are putting their data rates for MP4. I am of course looking for the sweet spot between files size and visual quality and I'm second guessing myself a bit. I recently decided that all my new video will be encoded in MP4, and I'd like to keep about the equivilent visual quality of my current archives which are MPEG-2 at around 2.6 Mbps (SVCD quality). Any guidelines on what data rate would give me (at least) SVCD quality?

Also, would you guys go through and convert the MPEG-2s to MPEG-4? Just trying to get a feel for what others are doing.

Thanks guys.
-Grover

[Uncle Skeleton]

I assume you mean SVCD resolution too? (480x480) 2.6 Mbps would be pretty low for DVD res.

What I do with the captures I like (the latest simpsons and other mediocre content I go lower), is 512x384, with 3ivx at QP5-QP3, which usually comes out at about 80-85 KBps. Audio I do AAC at 96 Kbps.

For software I use Cleaner for DV captures and DiVA/mAC3Dec for MPEG-2/ac3. These give mov files (which are technically superior to mp4 so I keep them), but you can easily use QTPro to passthrough them to mp4.

And a few random tips: don't use Apple's mpeg-4 codec (it sucks). cleaning up your source material before encoding can make worlds of difference (this includes cropping, deinterlacing, noise reduction, etc). and don't be a slave to the data rate; all content is not created equal, and it doesn't hurt to have some content come out small and others large even if they're the same length.

[grovberg]

Originally posted by Uncle Skeleton:
I assume you mean SVCD resolution too? (480x480) 2.6 Mbps would be pretty low for DVD res.

Yeah...I generally try to stick with standards to make sure everything will be interoperable. I have to be able to play the media on as many different systems as possible. DVD res isn't that much higher though, is it?

What I do with the captures I like (the latest simpsons and other mediocre content I go lower), is 512x384, with 3ivx at QP5-QP3, which usually comes out at about 80-85 KBps. Audio I do AAC at 96 Kbps.

Wow, that's WAY lower than the kind of numbers I've been getting (I was in the 300k area). I'm trying to use the 3ivx encoder now, but I'm not getting great results. Cleaner gave me totally garbled video. The 3vix options don't make a lot of sense either. You only seem to be able to make any choices about data rate with a single pass encode. I'm fine with waiting for a dual pass encoding, but am I then just at the whim of the encoder for data rates then? The file I got using the dual pass encoder was WAY too big (a gig and a half file for a 12 minute video). Am I missing something obvious?

Sorry if this seems very newb-ish...I feel pretty dumb not being able to figure it out myself.
-Grover

[Uncle Skeleton]

Originally posted by grovberg:
DVD res isn't that much higher though, is it?

720 / 480 = 50% bigger for NTSC
720 * 576 / (480 * 480) = 80% bigger for PAL

Cleaner gave me totally garbled video.

what were your input format and settings?

You only seem to be able to make any choices about data rate with a single pass encode. I'm fine with waiting for a dual pass encoding, but am I then just at the whim of the encoder for data rates then?

no, but you must set the datarate from the standard settings, not from within the 3ivx "options button" settings. In QuickTime Pro, that means in the first codec settings dialog, before you press "Options;" in Cleaner it means in the Video Data Rate section of the Encode tab.

The file I got using the dual pass encoder was WAY too big (a gig and a half file for a 12 minute video). Am I missing something obvious?

There is no possible way 3ivx could even fill that much space if you told it to. What was the res on that, and the framerate? and was the file watchable at the end? Sounds like there's something screwy with your Cleaner install. See if encoding something (small) from QTPro gives similar results.

If you neglect to set a datarate for any 3ivx setting besides "constant quality," it uses a default datarate (which is somwhere in the range of 200 KBps for 30 fps), which is like 10x lower than what you got.

[grovberg]

Originally posted by Uncle Skeleton:
720 / 480 = 50% bigger for NTSC
720 * 576 / (480 * 480) = 80% bigger for PAL

Yeah, I guess when you add in the percentages it is a fair amount more. grover=foolish.

no, but you must set the datarate from the standard settings, not from within the 3ivx "options button" settings. In QuickTime Pro, that means in the first codec settings dialog, before you press "Options;" in Cleaner it means in the Video Data Rate section of the Encode tab.

Ah ha. thanks for clearing that up. I was always worried that if you set data rate option in the "Options" section, that using the data rate setting on the encode tab would create some kind of conflict. In general, does one trump the other? Any thoughts on what might happen if you set conflicting data rates (say when using some other codec)?

There is no possible way 3ivx could even fill that much space if you told it to. What was the res on that, and the framerate? and was the file watchable at the end? Sounds like there's something screwy with your Cleaner install. See if encoding something (small) from QTPro gives similar results.

Looking at it now, I see that it's probably all audio (I tried another file last night and 40 minutes ended up 2.6 GB). In the Cleaner summary, the audio data rate says 1.4 mbits/sec even though that's not at all what it says in the audio tab (you can't even set MPEG-4 audio that high). I'm going to try to create the setting from scratch and see if that helps.

If you neglect to set a datarate for any 3ivx setting besides "constant quality," it uses a default datarate (which is somwhere in the range of 200 KBps for 30 fps), which is like 10x lower than what you got.

Good to know.

Thanks again for all the hand holding. I'm on a comittee that's looking to start an MPEG-4 video library, and I've been tasked with figuring all this out. One last big question...is 3ivx streaming compatible, or will I need to go back to the Apple MPEG-4 for that?

Thanks
-Grover

[Uncle Skeleton]

ah yes, audio. In some previous version of Cleaner (might have been 5) I used it to compress audio, then they broke their mpeg4 audio support and gradually made it less and less broken, but it's still not quite fixed, so I always use QTPro for audio now.

bitrate: you mean DivX? anyway, it's up to the codec, but I can't imagine it causing a problem. It will either use one or the other, and the logical choice is to use the one in the codec settings if there is one. But there's no reason it would cause something bad to happen.

streaming: 3ivx is written with streaming in mind. The only conflict I know of is that Apple's mp4 (not mov!) hinter is broken if you use the NVop (sometimes called VopN) option. If you intend to stream as mov files this doesn't concern you but if you want to transmux to mp4 and use Apple software to stream with, just disable NVop. As I understand it, NVop is a feature that takes advantage of consecutive identical frames by extending the duration of the first frame and discarding the others. Obviously even without this feature such frames will be very small, but with it they will be zero

[grovberg]

Just thought that I would post the solution I found for anyone here who might be wondering. Part of my problem was that I needed to come up with a simple set of instructions for our student employees to follow since they would be the ones converting several hundred DVDs to MP4 streams. All the bugs and problems with using cleaner and QTPro just made that seem like a loosing proposition. Then my one year old daughter managed to pull all my old magazines off a shelf, which included a DV magazine with a cover artivle about MPEG-4 encoders. After trying all kinds of MPEG-4 options, they chose Sorensen Squeeze (I didn't even know they were doing MPEG-4) and after using their demo software, I'm inclinded to agree.

It offers a wide range of options, but is very simple to use and delivers better looking files at smaller file sizes than either cleaner or Quicktime Pro using 3ivx or Apple. The difference is clearly evident...I was quite frankly shocked at how clear and small these files ended up. Being used to SVCD quality files being 200-250 MB for 12 minutes, I was shocked to see a file less than 100MB that was bigger in dimension and better looking. I sent in my order for Sorenson Squeeze this morning and can recommend it heartily. I'll post again if the full version is any different).

I also want to say thanks to Uncle Skeleton for all his hand holding. Even though I ended up not using the solution you suggested, I learned a lot and have a MUCH better understanding of the state of MPEG-4.

thanks.
-Grover