Compressor vs. ffmpeg vs. mpeg2enc

[DeusExMachina]

In all honesty, if I have the option of any of these three, a desired bit rate of about 4000 kbps, and no time constraints, which will be more likely to produced the best output, with optimal settings?

- Mark

[lordsmurf]

I hope the MPEG is 352x480 at that bitrate.

[major]

ffmpeg should produce the best perceptual output.

[DeusExMachina]

With standard DVD resolution of 720x576 PAL on already encoded digital files, 4000 kbps with VBR is more than sufficient for most purposes. I would suspect that few people would notice any difference between this and any higher bit rate. In fact anything much higher than about 6.8Mbps will actually discombobulate many low-end players.

Thanks major. As usual, answers are quick and helpful. This seems to be the consensus, that at lower bit rates ffmpeg usually produces better output, although sometimes with a localized increase in noise, whereas at higher bitrates, compressor and mpeg2enc sometimes come out on top, albeit much more slowly.

Would still like to see TMPGEnc ported to OSX, though, just to make a comparison.

[rack]

What about for H.264 encoding (Compressor vs. ffmpeg)? My experience is that Compressor is extremely slow, and the quality isn't so great, but it's the only H.264 encoding that DVD Studio Pro will accept.

[lordsmurf]

In fact anything much higher than about 6.8Mbps will actually discombobulate many low-end players..

Wrong. Not one ounce of truth to that.

[DeusExMachina]

Hmm… well, tell that to my $20 cyberhome 2000. Bails all the time on files encoded at CBR<6Mbps. Using VBR it can handle burst rates up to about 10.8Mbps, which is spec, but CBR? Not a chance.
To paraphrase Richard Feynmann, empirical data trumps theory.

Besides which, on many already encoded files, such as downloaded XVid Files, setting the bitrate above 3000 is useless. Try clicking best in the bitrate calculator. Anything into the blue zone provides NO useful quality.

[DeusExMachina]

To be more specific, if you are making glass masters and pressing DVDs into foil, you can have bitrates up to 10 Mbps or so. Of this you need about a Mbps or so for sound, more if you are using 5.1 or AIFF, and another for other tasks such as subtitle streams, angles, etc. This leaves you with a max safe video bitrate of no more than about 8 Mbps.
If you are using recordable media, such as DVD-R, this rate is much less, as many players, particularly cheap consumer decks, must expend processing cycles retrieving data from misreads. As such, anything above about 6-7 Mbps is asking for trouble. All this is assuming original, high resolution, high bandwidth, raw footage. I.e., if you are using DV video and pressing a glass master, video bitrate should not be higher than about 8 Mbps. If you are burning to DVD, then it should not go above 6.5 Mbps or so.
On the other hand, if you are converting already compressed video, such as downloaded files from the web, or DiVX files you have already made and want to offload to DVD, setting the bitrate higher than the max suggested bit rate gives you NO addtional increase in image quality. you can not encode to higher quality than your source. For most .avi files one finds online, this means that a max bitrate of between 1150 (for older VCD encodes) and 3900 (for high res DVD RIPS in DiVX) will provide you with the highest quality image. Anything more is just wasted sapce.

[t42]

I have really have a problem choosing between compressor and ffmpegx for dv->mpeg2 encoding. I noticed, that the picture after ffmpegx encode look generally darker than after compressor encode. And this difference is more visible after watching dvd on TV display. Is it a normal situation or should I change something in ffmpegx settings?

[DeusExMachina]

Wow, this one sure got raised from the dead! This is a very old issue, one I have posted a few threads about. Weird that you had found this thread and not the others

Anyway. The problem lies in the codecs used for mpeg-2. They assume a gamma of 1.8, but the mac uses a standard gamma of 2.4. Windows uses a 1.8 gamma, and much content comes from the Windows world, unfortunately. Technically, for viewing on computer monitors, the mac is correct, but since most things are 1.8, the resulting video files looked darkened. Currently there is no solution to this. Major is working on a complete Quicktime replacement that is supposed toaddress this, but it will not be available until the 1.0 release, so there is little that can be done at this point. I would switch to Compressor, but for many tasks it is VERY slow, and produces inferior output from low bitrate source files.

*sigh

[t42]

So,

DeusExMachina

do you mean that the ffmpegx picture can be adjusted to compressor just by changing brightness? Excuse em, but I didn't well understand what is gamma 1.8/2.4

[DeusExMachina]

It is not quite as simple as adjusting the brightness. he gamma value specifies a curve running through the brightness space. It denotes a varying increase or decrease in perceived brightness levels. Increasing brightness globally may make part of the spectrum display correctly, but will make others too dark or too bright. Since ffmpeg (as opposed to ffmpegX) was NOT written primarily for the mac, there is not much motivation to have it handle gamma in a more generic way. Rather it just assumes all source files are from machines with a 1.8 gamma. So as of now, there is nothing I have found to correct this problem (other than using a PC .)