XVID Support?

[Mikgerdan1991]

Hi, first post! 

Well, currently, I have a Zen Vision M, and I am considering switching to the iPod Video just so I can get Rockbox on it for all the features it has. (How is Rockbox going for the Zen, anyway?) Anyway, the ONLY thing keeping me with the Zen is XVID support. In my opinion, it's the best video compressor, and the file size is extremely low compared to MPEG. Is there any chance of XVID support for Rockbox, or is work already possibly being done?

[Llorean]

XVID is significantly more computationally complex, and is very unlikely to even come particularly close to full speed on the iPod Video. While nobody's working on XVID if you want to watch video on Rockbox the Gigabeat players are much better suited to it and are more likely to be full speed if someone does do the work  for XVID.

As it stands, people have suggested it, but nobody is apparently interested in putting in the time to do it.

[Mikgerdan1991]

Aw, that really sucks, I'm sure file size is a lot of people's concerns with MP# Video Players these days, with most of them being around 30-60 GB...With MPEG, you couldn't store a whole lot of movies on a Rockbox device. 

Ah well, I guess I'll stick with my Zen, more space means more videos. 

I'm not a coder, nor do I know anything about it, but would it be that difficult to put a new video codec onto Rockbox?

[Llorean]

At ~500MB per movie at a quite good quality, I can store 60 movies on a 30GB device. That's not really "not many."

It's not really as simple as "just putting a codec on." You'd need to do a lot of optimizations specific to the architecture of the player, and possibly convert it to fixed point.

[saratoga]

I'm not a coder, nor do I know anything about it, but would it be that difficult to put a new video codec onto Rockbox?

Full Xvid support is basically impossible given the CPU on the iPod video. 

And anyway, you overestimate the savings with Xvid.  The difference in file size is fairly small.  The wiki recommends 0.3 bits/pixel for MEPG2.  Typical Xvid is around 1.5-2 bits/pixel.

[Mikgerdan1991]

I don't know, I converted a 2 minute XVID movie (at 256 vid, 128 mp3 audio), which was around 3 MB, to MPG, and it became 7 MB. And it was even pretty bad quality....

Ok, forget about the iPod Video, then. Just XVID on any player maybe? I'd be willing to switch to anything for Rockbox, I just didn't want to convert ALL my videos to MPEG...and lose space or quality in the process.

[cool_walking_]

As said above, XVID could be possible on some of the other targets, but it needs someone to code it.  Rockbox developers are just individual people who work on whatever they want to work on.

[Mikgerdan1991]

I know. 

It was just a suggestion, though. No big deal if I don't get my XVID. 

A very strong suggestion...But a suggestion, nonetheless.

[Llorean]

It sounds like maybe you didn't use a good conversion tool/settings. Are you sure you converted to MPEG-2, not MPEG-1, and did you spend much time experimenting with settings? There's a lot of things about MPEG-2 you can tweak to get a bit more out of it for the bitrate.

Also, it really helps to watch them on an actual player. Because they're limited to 16-bit color, and much smaller screens, some of the quality differences just aren't nearly as visible on the actual portable player.

[Mikgerdan1991]

Well, I went with your MPEG 2 suggestion. I got that same file i tried before down to about 5 MB, but still, at pretty bad quality. I can't try it on my player because it doesn't have MPEG 2 capability, but I tried it at just that size, and it wasn't great.
And yep, I have a pretty good converter, I can 'tweak' a lot of stuff, and it's still about 60% larger (in file size).
Maybe you can recommend the one you use?

[Llorean]

I just use ffmpeg. As I said though, it'll make a larger difference if you watch it on a player.

One thing you definitely need to not do if you're watching it on the PC is stretch the window at all. Play it in its native 320x240 or 320x160 size, after conversion. I'd still expect the filesize to be larger, but when you can only watch a few hours per charge maximum, even 30 movies would be a considerable amount, let alone the approximately 60 I would expect.

Storage space ought only to be a problem if you're going for a very extended period with an inability to sync the device.

[Mikgerdan1991]

Well, I like to have all my videos on my Zen...and with XVID right now, I can. Right now, 16 GB in music, and about 27 in videos. I don't know if I'd have any space left with MPEG...

But thanks for the advice, I'll try ffmpeg.

[soap]

Well, I like to have all my videos on my Zen...and with XVID right now, I can. Right now, 16 GB in music, and about 27 in videos. I don't know if I'd have any space left with MPEG...

Are those full-resolution XviDs?  (512x384 or so)
If so, when you kick them down to half-framerate, 320x240 the files will be smaller than what you currently have, even if you double the bits-per-pixel.

[Mikgerdan1991]

Nah, I make all my videos 400x300, usually 256 kbps. Or kbs. Whatever the unit is.
I get pretty decent quality at such a low file size with XVID. 

[soap]

Still enough that at the same bitrate, at 320x240 I would expect no visible difference.
1.576 times the needed number of pixels = plenty of bandwidth to play with.