MP4 export and bitrate

karlh10 wrote on 2/11/2015, 2:28 PM

Hi -

I am using MEP2015Plus and my export format of choice is MPEG-4. My computer is old so I'm using the 32-bit version and the MainConcept codec.

My question has to do with bitrates. All over the internet I find people claiming that you can go as low as 1200 kbps for a 640 x 480 video when using the h.264 codec. I have plenty of 480p MP4 videos that I've downloaded off the internet which have a similarly low bitrate....and crystal clear quality. I've seen 720p down around 3000 kbps no problem, and 1080p as low as 3600 kbps with no artifacts or noticeable blurring. I use another program called MKVConverter to export to MP4 at low bitrates with great success. I can't seem to get these results with the MEP export.

For the sake of example, I used a 5 second 640x480 MPG clip that came off a digital camera. Unfortunately, I didn't get adequate results until I was up above 5000 kbps.

Here are some screenshots. Pic 1 is a screen capture of the original MPG. Pic 2 is a screen capture of the exported MP4 at 1200kbps, which is very blotchy. Pic 3 is the Main Settings screen for the MainConcept export.

Besides just telling me to use a higher bitrate, does anybody have any idea why I'm getting bad results? Thanks! \karl

Comments

johnebaker wrote on 2/11/2015, 4:13 PM

When you export as mp4 which preset are you using from the dropdown in the export dialog?

To see all the available options check the option circled as shown below

John

karlh10 wrote on 2/12/2015, 10:06 AM

Hi John - I mostly don't use the presets, because I usually can't find a good NTSC match for my desired output.

I will try one when I get back to my home computer later.

Thanks for your response! (...I now notice that I posted this in 'Topics' instead of 'Questions'; hope that's OK)

\karl

karlh10 wrote on 2/13/2015, 9:12 AM

John you've done it again! I am successfully exporting MP4s (640x480) with only a 1500 kbps bitrate. (I was not using a Preset until you suggested it).

It is a bit mysterious, though. It seems that using an export Preset is doing something behind the scenes that gives way way better results. When I did the export with no Preset and just set everything (I understand) manually, like resolution, FPS, bitrate, my exported MP4 had terrible quality. For an experiment, I used the 640x480 25FPS 2000kbps preset and much to my surprise I got a perfectly detailed MP4. I switched to 30FPS dropped the bitrate to 1500 and still got a great result. It's when I started messing with Performance quality (increasing it!) that the MP4 went sour again. I'm not really sure what is going on, but glad that I now can get excellent MP4 output.

So, the Main Settings dialog of the MainConcept export has got me puzzled. Sometimes I will change settings (like the GOP structure), click apply, click OK and OK, then go back into the Main Settings and see that some of my settings have reverted back to some default value. John, any opinion on that, and the possibility that something is going on behind the scenes that I can't see, but maybe the presets are altering?

I made my own preset as an alteration of an existing one, and things look good.

Also, the pic below is the Advanced Settings tab, as I'm sure you'd recognize. I know it's been asked before, but what is that screen for? I change values and they revert back to their defaults when I reopen the dialog. I'm an NTSC guy, so I'm a little bothered by the permanent presence of 25.0 FPS. Any thoughts?

Thanks a million, John! You are the ultimate MEP man! \karl

johnebaker wrote on 2/13/2015, 1:38 PM

. . . . It seems that using an export Preset is doing something behind the scenes that gives way way better results. . . . .

The presets are optimised for the particular format, resolution and target audience/use. It is too easy to end up with settings which are suboptimal or even conflict with each other.

Happy exporting.

Cheers

John

Scenestealer wrote on 2/14/2015, 4:18 PM

Hi Karl

My experience over the years has been similar to yours. Any increase to the quality setting in the main window has resulted in very blocky degraded output, almost as though there is a bug.

The advanced tab seems to be locked even though you can make changes there - which as you have found don't stick, and some appear to be irrelevant to the export format.

As John has suggested the presets work pretty well and are often tweaked by Magix as can be seen in the changelog of the latest MEP2015 patch :- •Optimized various MPEG-2 and MPEG-4 encoder presets.

Changes to the basic main settings like frame rate and bitrate are possible, and can be beneficial as you have found.

Peter

karlh10 wrote on 2/18/2015, 2:20 PM

Thanks for the info Peter. Glad I'm not the only one!

\karl