H.264 vs. Sorenson3

Brian Wells · November 16, 2005

Even worse is the situation where you have downscaled your video by some arbitrary amount to get it to 320 by whatever, and the interlace fringing has been screwed up by the resample.

What about 24P Quicktime's converted to 1/4 resolution (320x240) H.264's? Will those at least have the potential of looking alright? BTW, I'm learning a lot from this thread.

Gordon Highland · November 16, 2005

Yes, I use the term "progressive" loosely. What I meant was "progressive scan" Err, 24P. What other kind of "progressive" is there? I'm asking because I don't know.

Oh, ok then; so we were on the same page. I thought you meant "progressive download," which is a term used in the compression process and a selectable option in Squeeze, etc. It's sort of the opposite of streaming. You get consistent quality playback because the clip gets buffered before it starts playing and will stop as needed instead of just beginning instantly and dropping the frame rate to maintain realtime play.

Life got much better when I started shooting progressive scan, AND I prefer progressive downloading most of the time. I haven't experienced any problems with odd % pixel scalings in the 24p world, but I really had to watch it with interlace. Most of the time I'm doing 320x240 @ 15fps or 12fps. 12 is too few frames in my opinion, but if I have to hit a target (<200Kb/s in my case) I'd sacrifice some temporal resolution for spatial resolution ? in other words, fewer frames that look cleaner each, rather than smoother action that was blocky and pixellated. That's just personal taste, though. I have no experience compressing to H.264 yet.

Phil Rhodes · November 16, 2005

Hi,

> What about 24P Quicktime's converted to 1/4 resolution

What sort of 24p Quicktimes? 24p quicktimes that are 24 frames a second? 3:2 pulldown quicktimes? 24pA quicktimes that are 30 with a slightly different type of pulldown?

Think about it. You're rescaling the image. If it has interlace artifacts in it, irrespective of what format it's pretending to be, that's going to cause you problems - and you shouldn't be deinterlacing by resampling it anyway, as you won't get correct motion blur.

Phil

Hi,

> Are all these options available in the Windows version, Phil? Is the Main Concept encoder any better? How?

I don't know, I generally use the exporter in Premiere to do this sort of work. Since I'm mainly doing Windows Media, which uses the system-provided compressors, it seems to work OK.

The reason I use windows media, if anyone's interested, is that it neatly sidesteps all these problems. The codec is great, there are a wide variety of excellent audio codecs available (which is much less the case with Quicktime) and it has a kind of just-works reliability that I find quite useful. All this poking about with MPEG-4 under Quicktime is rapidly turning it into a complete chore to use.

Phil

November 16, 2005

I only have a minute but:

I agree about the sonic abilities of wmv files. They sound way better than anything else that other video codecs offer in their audio. I would offer a caution however that, they sound better if you download them than if you stream them. I don't know why this is but its true. This is a poor example but I'll post it anyway; I had cleaned-up a terrible concert video shot by someone in the audience with a VHS cam almost 25-years ago. The person shooting it had a filthy lens and knew nothing about exposure, white balance or filters. The footage is also about 6th generation of dubbed VHS tapes. To call it washed out is a kindness. And the audio isn't much better. Its also at a low bitrate. However, if you try to stream this for a minute or so and then download it instead and watch the download, it'll give you a good idea of how the audio sounds better downloaded than streamed. Again, I don't know why this is so:

Phil Keaggy - Live 1981 w/ The Glass Harp (7mb-wmv)

Another caution when working with wmv files: Make sure you convert the audio to 16.44.1 first. It screws-up audio at any other resolution than 44.1 because it doesn't have a built-in dithering scheme. I would also avoid converting to wmv from Premiere. I'm not sure why but wmv video tends to look better when converting it via Windows Media Encoder 9 or from Windows Movie Maker.

Phil Rhodes · November 16, 2005

Hi,

WMV files usually contain several streams of audio and video - that's why the files are huge, but the streams are tiny. Most server/player combinations are designed to negotiate to play whatever stream seems most appropriate to the available bandwidth.

The picture quality differences you're seeing can only be to do with the presets you're using - the same software is doing the processing in each case.

Phil

Marek Stricek · November 16, 2005

I always use two pass encoding and I also check the "frame re-ordering" box as was suggested for best results.

Are all these options available in the Windows version, Phil? Is the Main Concept encoder any better? How?

Yes, the Windows version has "frame re-ordering" and there is "multiple pass" instead of "two pass" (but it is probably two pass anyway). So I assume there should be no difference between Win and Mac in the encoding process.

Regarding the questionable quality of Quicktime H.264 encoding, it might be due to a fact that the Quicktime encoder is not using all the techniques available in full H.264 standard. (see Encoders section in http://forum.doom9.org/showthread.php?t=96059 )

November 18, 2005

"Most server/player combinations are designed to negotiate to play whatever stream seems most appropriate to the available bandwidth."

Yeah, I figured it must be something along those lines. Also, the video portion doesn't seem to be as negatively effected as the audio when streaming. I guess they figured people would rather sacrifice audio than video.

Brian Wells · November 19, 2005

Regarding the questionable quality of Quicktime H.264 encoding, it might be due to a fact that the Quicktime encoder is not using all the techniques available in full H.264 standard. (see Encoders section in http://forum.doom9.org/showthread.php?t=96059 )

Thank you. I appreciate the link. There's much more to it than I thought.