[Carniphage]

I am using the XBMC on the AppleTV. Mainly to play 720p content (MP4)
These are files that play back fine using the native (Quicktime-based) playback software.

But under XBMC something interesting is happening. The brighter the scene, the slower it plays back.

Scenes in bright sunlight struggle to play. The audio gets out of sync, and its pretty unwatchable. Wheras darker night-time scenes play back fine.

This seems a little odd.

So most of Entourage, with all that harsh Californian sunlight, looks pretty choppy. While True Blood, with all that after-dark, kinky vampire stuff plays back fine.

C.

[davilla]

I am using the XBMC on the AppleTV. Mainly to play 720p content (MP4)
These are files that play back fine using the native (Quicktime-based) playback software.

But under XBMC something interesting is happening. The brighter the scene, the slower it plays back.

Scenes in bright sunlight struggle to play. The audio gets out of sync, and its pretty unwatchable. Wheras darker night-time scenes play back fine.

That is interesting, it's a compression issue. Can you give more info about the profile and bitrates for these problem 720p files?

[Jezz_X]

I'd say its probably more to do with detail in dark you really don't see alot of detail thus less Bitrate and in bright light all the detail shows up thus higher bitrate

[Carniphage]

That is interesting, it's a compression issue. Can you give more info about the profile and bitrates for these problem 720p files?

One example. Entourage 504
1280x720 @ 23.98fps
h264
average bitrate 3758kbit/s
varying from.... 3000kbits (low) to 7000kbits (high) In sunlit scenes! (Looking at VLC's playback monitor)

I have the XMBC memory buffer cranked up to max - and my 802.11n network is plenty fast enough.

During the fast sunlit scenes - frames get dropped visibly - and audio gets out of sync - perhaps as much as 2 - 3 seconds.
When the scene ends or the action slows down, XBMC is good at restoring sync. Impressively the player fast forwards video until the audio is back in sync.

The file above was created using VisualHub (RIP) - which has a preset specifically for the AppleTV. This preset pretty much guarantees the best quality which will reliably play. The AppleTV's built in (Quicktime based) player can cope with this file.


C.

PS. This is not a criticism of the XMBC. You guys are doing a great job.

[Gamester17]

Video encoding fun fact; the darker a scene is the higher bit-rate it requires to look good (ie. not not show any artifacts)

[Carniphage]

Video encoding fun fact; the darker a scene is the higher bit-rate it requires to look good (ie. not not show any artifacts)

Certainly a lot of video shows nasty posterization/quantization artifacts on smooth dark areas.

C.