Recommended Quality Setting for Pocket PC?

[Yo]

I use AutoGK to make small movies from my DVDs to play on my Pocket PC. (2210, running Windows Mobile 2003). Using Betaplayer 0.4 (nice new freeware player, BTW) to play them. The screen size/resolution is 320x240, so that is my target resolution for the video, to fill up the screen.

With some programs I have used before to make movies for PPC (like Windows Movie Maker, which makes .wmvs to play on WMP for PPC), there is a profile (or multiple profiles) one can choose for PPC. There isn't that with AutoGK, so I have usually guessed based on file size. I noticed that with other programs a two hour movie encoded with the full screen PPC profile often took up about 200 MB, more or less of course, depending on the movie. So with AutoGK I have specified the desired file size as about 100 MB per hour of movie. That often works out OK.

Last night I encoded a one hour movie, so set the file size to 100 MB, and the video came out terrible. (I guess each movie has different compression potential.) So I'm thinking it would be better to decide on what is a good quality level to set for PPC, rather than setting a file size.

The things to consider therefore, would be--that the desired resolution is 320x240, and that PPCs do not have a lot of storage space, so one wants to keep the file size on the small side. Therefore, probably the lowest quality setting possible at that resolution that would keep a decent acceptable video quality. (The video I encoded last night is not acceptable.) Not going for high quality, but minimum acceptable at that resolution. (I don't know if there are other factors to consider in encoding for PPC.)

I know that one could decrease file size also by reducing the audio quality. In this case, since in some of my videos music quality is important, let's take it that one is keeping the default music quality, VBR MP3 at about 128kbps.

Any suggestions for a default video quality level for 320x240 PPC screen playback?

[len0x]

Why don't you just set fixed width of 320 and quality of 75 (as default) and do one pass encoding? quality upto 60% with xvid should be acceptable as well...

[Yo]

Originally posted by len0x
Why don't you just set fixed width of 320 and quality of 75 (as default) and do one pass encoding? quality upto 60% with xvid should be acceptable as well...

Thank you for the suggestion. I'll try it, and see what kind of file size I end up with. With a two hour movie, a resolution of 320x240, and a quality setting of 60%, in what range do you think the file size of the movie might fall? (I know it could vary according to the compressibility of the movie, but an approximate range?)

What do you mean by "do one pass encoding"? I don't recall seeing a choice in AutoGK for one or two pass. Doesn't AutoGK always do two pass, and doesn't that create a better quality for the file size? (Of course, with the disadvantage of it taking more time. I find the best time to start an encoding with AutoGK is before going to bed at night, as it takes hours!:D ) Why did you recommend one pass encoding in this case, and how do you set it?

BTW, thank you for actively supporting your freeware product in these forums! That's great! :)

[len0x]

if you want to have fixed width and always the same quality for all your sources then quality based encoding does the job - it does 1 pass encoding btw (while in target size you always have 2 passes).

[Yo]

Originally posted by len0x
if you want to have fixed width and always the same quality for all your sources then quality based encoding does the job - it does 1 pass encoding btw (while in target size you always have 2 passes).

OK, thanks. It does look like quality-based is a better choice than target file size. Would lower than 60% normally produce poor quality?

Again--what (approximate) file size (or range of file sizes) would you estimate a two hour movie encoded by AutoGK at 320x240 resolution with quality setting of 60 to have?

[manono]

Would lower than 60% normally produce poor quality?

Your chosen resolution is already guaranteed to produce poor quality. Maybe it's OK for the small screen, but not for a larger screen.

what (approximate) file size (or range of file sizes) would you estimate a two hour movie encoded by AutoGK at 320x240 resolution with quality setting of 60 to have?

I (nor anyone else I know) don't encode at that resolution, so I wouldn't know. Depending on the movie, I'd say anywhere from 150 MB up to 1 GB or so. As you yourself said, "I know it could vary according to the compressibility of the movie", so why don't you try it and see. It'll only take 1-2 hours to find out.

[Yo]

Originally posted by manono
[B]

Your chosen resolution is already guaranteed to produce poor quality. Maybe it's OK for the small screen, but not for a larger screen.



Well, 320 x 240 resolution on a 320x240 pixel screen I wouldn't say is poor quality.

A lot of people make such movies for Pocket PCs and other PDAs. This will be increasing with the increase in the "portable media center"
type of thing, which also have very small screens.

It's actually the only reason I use programs such as this to make small compressed videos. On the TV or larger computer I can watch the original DVD. The reason for encoding a small video file is to watch it on the PPC.

If you look at Pocket PC web sites with forums, like pocketpcthoughts (http://www.pocketpcthoughts.com), or newsgroups like microsoft.public.pocketpc.multimedia, you see many questions about how to do this, how to rip a DVD to a small video file for the PPC. A program like AutoGK is a natural for that. It would help if there were some kind of profile for PPC though.

[Yo]

Originally posted by len0x
Why don't you just set fixed width of 320 and quality of 75 (as default) and do one pass encoding? quality upto 60% with xvid should be acceptable as well...

I did some experimenting, and you'll be shocked at the results--I found an acceptable file size-quality trade-off for Pocket PC (at a 320 fixed width resolution) more at about 20-30 quality setting.

No, the quality is certainly not perfect at such a setting. One sometimes notices artifacts in the video, but not most of the time. Seeing it on the small 320x240 screen makes a difference--a quality might be acceptable on a small screen like that, which would not be acceptable on a larger screen.

Also--please note--PPCs do not have hard drives. Very little built-in memory, which serves for program memory as well as storage. And memory card slots. My IPAQ 2210 has both an SD slot and a CF slot. More common in newer models, however, is to only have an SD card slot. Therefore, the size requirement for such a movie is completely different than for putting a movie on one or two CDs, etc.

Does no one else reading this board use AutoGK (or GK) for making very small movies for PDAs, Smartphones, etc.?

[timbur]

I did some experimenting, and you'll be shocked at the results--I found an acceptable file size-quality trade-off for Pocket PC (at a 320 fixed width resolution) more at about 20-30 quality setting.
For my Archos 420, I use 320 fixed width and 25% quality. Works great for TV shows (Buffy, ST:Deep Space 9). The movies I've encoded so far are OK with these setting too, although I have not watched those in a while on the Archos.
No, the quality is certainly not perfect at such a setting. One sometimes notices artifacts in the video, but not most of the time. Seeing it on the small 320x240 screen makes a difference--a quality might be acceptable on a small screen like that, which would not be acceptable on a larger screen.
I concur. I tested encoding at 640 width versus 320, and different quality settings, and I couldn't see any real difference on the small player.
Also--please note--PPCs do not have hard drives. Very little built-in memory, which serves for program memory as well as storage. And memory card slots. My IPAQ 2210 has both an SD slot and a CF slot. More common in newer models, however, is to only have an SD card slot. Therefore, the size requirement for such a movie is completely different than for putting a movie on one or two CDs, etc.
Mine has a 20GB HDD. But I like to carry a season of Buffy and DS9 with me at a time, which will eat up most of the HDD.

[edeus]

There are quite a few programs out there specifically designed for PPC Yo.

I suggest looking at Pocket DVD, Pocket DVD Studio, or the freeware PocketDivxEncoder (Great name). The premise for these products is specifically low resolution PPC, Archos, et al., devices. Supposedly they go one step further and make them "perfect" for PPC.

Personally I find AutoGK a much more professional program than these (if you dont need any of the cropping/ratio conversion/wmv encoding (for older slower PPC's that cant play smooth divx)).

My experience of late has been as follows:
VBR MP3 is obviously the way to go audio wise, but if you dont need the stereo sound - movies lacking much "immersivity" i.e. Cartoon's - in Hidden options select mono sound. It will cut the audio track size in half. Theoretically if you do this, a 64K Mono sound track = quality of a 128K Stereo track except without the "stereo". (According to said PPC DVD to DIVX software makers - why isnt there any cross channel compression???).

Many PPC devices you can drop the FPS. Do some tests to see where the sweet spot is for your PPC. Some cant display more than 15-20, others, can play the full 24-30. Apparently this has the same effect as combining audio tracks to mono, you can use half as much video space if you have 15fps instead of 30. (Personally: I believe this is true to an extent, but not a perfect 50% and would be motion dependant YMMV)

Finally 2 pass/fixed size would produce the best quality results especially important for these low bitrate encodes. This is perfect for people with SD Cards of a certain capacity (256, 512 et. al) but a quality based 2 pass encode would produce better results (From your experience using say 35% quality then AutoGK using the first encode locked file size to then do a fixed file size encode. Not sure what is possible - I probably am remembering AutoGK incorrectly here)

My experience with file sizes to produce balance between size/quality for a full length movie average 90 minutes (320x240@24fps):
128MB - Low quality, can be OK if you use 32-64K VBR Mono sound. Excellent if you want more than one movie on a small memory card.
256MB - Good quality, Select any type of sound and you will get a good result - but you will be lowering movie quality.
300-400MB - Excellent quality, near DVD quality. Any larger you will notice very little quality improvement on a 320x240 pixel device. Perfect option for those with large memory cards (I bought a 2GB one to not have to worry 'so much' about size)

Because AutoGK doesnt publish average/min/max bitrate's I find it a little hard to give you an accurate recommendation. If you do decide to do it with something else the best quality to size is about 300kbit/s video bitrate. Add audio quality to taste. 300-350MB is what you would expect.

As some audio reference here is a video I compressed with different settings:
Input dir: C:\dvds\YOU_GOT_SERVED\VIDEO_TS
Custom resolution settings: fixed width of 320 pixels
Codec: XviD
Target size: 250Mb

Custom audio settings: VBR MP3 with average bitrate: 128Kbps
Audio size: 87,732,600 bytes (83.67 Mb)
Overhead: 5,446,016 bytes (5.19 Mb)
Video size: 168,965,384 bytes (161.14 Mb)

Custom audio settings: VBR MP3 with average bitrate: 64Kbps (Mono)
Audio size: 21,366,175 bytes (20.38 Mb)
Overhead: 5,446,016 bytes (5.19 Mb)
Video size: 235,331,809 bytes (224.43 Mb)

Custom audio settings: VBR MP3 with average bitrate: 128Kbps (Mono)
Audio size: 41,419,200 bytes (39.50 Mb)
Overhead: 5,446,016 bytes (5.19 Mb)
Video size: 215,278,784 bytes (205.31 Mb)

[homermaster]

First of all, betaplayer has been updated to TCPMP (The Core Pocket Media Player) which has versions for PPC and Palm platforms. I would recommend updating that program.

Second, I have been using AutoGK and TCPMP for months now and, with a few exceptions because of movie length, have set my encodes at VBR 192 MP3 and a target size of 484 MB (the actual size of a 512 MB card).

It is most likely that you will not be as interested in the extra info required for the 192 MP3 so you can save some extra bits for video by going to 128.

I have two 1 Gig cards and am more interested in what I can fit on the card and 2 movies per card is the best trade off for me.

[JnZ]

Hm,

I have iPaq 4350 <320x240 res. display> and use this (I'm watching ST: Voyager now):

Encode with XviD: 1-pass, Q4, Bulletproof's low biterate matrix, VHQ 1, others at default.

Audio: VBR Mp3@96khz <64-128> in LAME encoder.

I've got about 70-80 MB file (per 45min clip). Encode takes about 10mins on my Athlon 64@2400MhZ, so nice speed.

My iPaq can play about 6 epizodes of ST:Voyager (6x45min) to one recharge of battery with this settings.

I've use my little program Pocket XviD encoder, which can encode avi's automatically to this setting. I'm still working on this program,maybe after finish some things, I free this progs on this forum for testing, if someone have interest.

I think, that, this is best speed vs quality settings.

JnZ