[jingai]

I'm encoding some home videos currently and have had a lot of trouble figuring out why XBMC insists on playing back my 1080p30 videos as 1080p24, and thus dropping frames and causing jerky playback.

I'm using iMovie for my editing and exporting via x264encoder (latest). If I export the source material as 720p30, XBMC plays it back normally. If I export as 1080p24 it also plays it back normally (no dropped frames), but of course isn't as smooth as the 720p30 version.

If I export at 1080p30, XBMC drops frames to maintain 24fps; that is, hitting O shows that the source video is 29.97fps, but it plays it back between 22-25fps, dropping a lot of frames to do so.

mkvinfo on the MKV file shows it is 29.97 fps, and my Linux box plays it back fine in both VLC and mplayer.

I've tried this with the 3.6.0 CHD driver as well as one built from SVN r174. Both exhibit the same problems. The card is a 70015 purchased from Logic Supply about 3 months ago.

Is this a limitation of the Broadcom CHD card, or could I possibly be doing something wrong? I've tried flicking every switch I can think of in the encoder and nothing makes a difference with regard to the jerkiness of the video, besides encoding it as 720p30 or 1080p24.

Here is the log file during the testing. The first two video plays are successful -- the third is the problematic one. It shows no errors in the log, but I assure you it's dropping frames to attempt to maintain 24fps.

I can supply some test video if necessary.

-j

[jingai]

I've figured out what's causing the drops -- if I choose either GLSL or Basic Shaders rendering methods, then it tries to maintain 24fps on 1080p30 videos. If I choose Software, it plays them back normally, albeit with 100-115% CPU usage.

I've had the rendering method set to Auto Detect for quite some time, which explains why it would work some of the time and not others (and made it difficult to figure out what changes I'd made were making it behave differently). I've also noticed that most of my TV Shows and other movies are 1080p24, but last year I did have some frequent problems with certain episodes Mad Men and Californication that I think I can attribute to this issue. We would generally reboot the computer until the problem went away, but now I think it was just choosing the Software renderer whenever it did work.

It'd obviously be nice to get the GLSL renderer working so it's not cooking my Mac mini all the time. Any ideas?

-j

[jingai]

Oh, and FYI, I'm using a nightly built 2011/04/22. But the problem has persisted with all of the many nightlies I've built over last 4 months, as well as the official releases.

I am not sure if the same problem existed before Dharma because I only got a camera capable of 1080p30 as of December 2010.

-j

[bobo1on1]

I've seen more reports of this, for some reason the YUY2 shader runs way too slow.

[jingai]

Hmm. Well, as I said before, if any developer wants some sample material that is guaranteed to illustrate the problem, I'd be happy to work up a small clip. I'm not 100% sure if all 1080p30 videos show the problem, but the clips I've made myself and the limited number I've gotten elsewhere all seem to.

-J

[jingai]

As of git 57d61a94, this is suddenly working fine. It may have been just that I rebuilt from a clean source tree, though.

At any rate, my home movies now play back at 29.97 fps as they should, with 60% CPU utilization. Yay!

-j