Encoding RV10 for PocketPC

[Luke_A_P]

I'm trying to find an optimum combination of format and settings for creating video for playback on PocketPC. My test device at the moment is an iPAQ 4150, (320x240 screen 400MHz Xscale processor).

I am interested in Real Video 10 because of its excellent performance at low bitrates. However I am having trouble finding settings that will playback perfectly. If anyone can give me any recomendations based on knowledge or experience I would be very greatful.


For those who may be interested here is my take on the competitors in the pocketPC video world:
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Windows media is not really an option since the playback performance of the PocketPC player is so poor.
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The freely available PocketMVP player can playback full screen (320x240) divx/xvid video very well. It can handle bitrates high enough to make artifactling barely noticable on the small screen (~250kbps video I find). That does lead to quite large file sizes though.
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With RV10 I have found that some files play back very well whilst others will stutter quite badly, I am trying to work out what causes the problem. The trouble is there are so many variables to play with that it becomes quite tricky to diagnose.

I am using 2 pass encoding with fixed total bitrate, all clips are resampled to 320x"whatever is appropriate for the aspect ratio", the clips have audio in the form of 56kbps real audio, and they are all at 25 or 24fps. Also note all the files play back well on PC it is only the PocketPC which suffers the stuttering.

The problem doesn't appear to be related to the average bitrate, I made some files with ~200kbps video which playback fine, and some at ~140kbps which don't.

Peak bitrate could be the issue but I have tried turning it down and it seems to have made no difference.

One factor that seemed to make a difference was changing from "normal motion video" to "sharpest image". I made files from the same source clip using each of these settings and at at very similar bitrates, only the "sharpest image" one stuttered.

(The comparison was not perfect, because of a mistake on my part the audio track was blank on the "normal motion video" clip, The audio track was present but it was empty.)

I was expecting this setting simply to control the processing of high frequency information in the image in a standard "blurriness vs. artifacts" relationship but I can't see why that should have much effect on playback performance. Can anyone explain more about what this setting does?

Any other input would be great too.

Thanks

Luke

[cypher_soundz]

Not directly related , but I would go for divx5.x.x , its not the best , but pocketMVP plays it well, I use Gknott , just rip with 2pass setting and b frames, 320x240 for widescreen.
I find that leaving it as a 25fps frame rate does drop a few frames (I think its when the processor is stepping up from 200mhz to 400mhz in auto mode) but not noticeable, and @ that size you cannot see any artefacts.
Sorry I couldn’t help with the real video, but I hope this has helped a little.
Regards
Cyph

[Luke_A_P]

I totally aggree with you that DIVX/XVID work extremly well with poketMVP it is a very good solution. It works well full screen at 25fps and I use it, but I do think real video is able to provide acceptable looking output at lower bitrate than DIVX, and on a pocketPC filesize is always important.

I have done a bit more experimenttation in the mean time and I have found that realplayer for pocket pc can handle realvideo10 that has about half the pixels of full screen (~40kpixels at any aspect ratio) without sound. If you add sound or inrease the image size it starts skipping badly.

I also have some realvideo8 files that I have downloaded, these are 320x240 with 44kbps sound and 225kbps total). These playback perfectly, however if I try to produce the same format using realvideo8 with the same size and bitrate they skip on playback. So I am wondering whether the problems are caused by something I am doing wrong when creating the files, perhaps the player can handle full screen realvideo10 if you do it right. That would make it a very attractive solution.

I also wonder if the real player for pocketPC could be sped up by a recode, or may be a plugin for PocketMVP similar to realalternative for windows but who knows.

Luke