[jumpcuts]

Hello,

I'm a Plex user and I've been trying XBMC 9.11 Camelot for a couple of days on my Mac Mini (2.26GHz w/4gig - OS 10.6.2) and I really like what I see.

However, I`ve found that high bitrate 1080p MKVs don`t play smoothly on XBMC and I can`t find why. Those MKVs are made from original discs with MakeMKV.

The same file would play smoothly on Plex without any h.264 Speed Boost. The files are located on a gigabyte NAS.

I see that the cache settings as been removed from XBMC, so I would guess that it as nothing to do with this... so I`m looking for something else.


Here`s my log.

http://pastebin.com/m31ce78c6


Thanks for your time.



Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : [email protected]
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Muxing mode : Container [email protected]
Codec ID : V_MPEG4/ISO/AVC
Duration : 2h 1mn
Bit rate : 23.3 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Resolution : 8 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.470
Stream size : 19.7 GiB (95%)
Color primaries : BT.709-5, BT.1361, IEC 61966-2-4, SMPTE RP177
Transfer characteristics : BT.709-5, BT.1361
Matrix coefficients : BT.709-5, BT.1361, IEC 61966-2-4 709, SMPTE RP177

[althekiller]

16:17:14 T:2959818752 M:2495844352 ERROR: ffmpeg[B06B4000]: [h264] number of reference frames exceeds max (probably corrupt input), discarding one

Those certainly aren't helping you, could be an encoding problem on makemkv's end or demux problem on ours. Perhaps you could provide a small sample that reproduces the issue?

Your system is quite weak to be decoding high bitrate 1080p h264 video. Odds are plex has skip_loop_filter set very high which improves performance at a cost of quality. You can play with it in XBMC via advancedsettings.xml. The wiki is your friend should you chose that route.

[RckStr]

Does high bitrate make a large impact? I tried ripping some blurays using makemkv and ive noticed some of those play jerky. The filesize is generally twice of those ive just downloaded (wich play fine).

[althekiller]

Yes.

I suggest you head over to doom9.org for encoding info. They know more than is healthy on the subject.

[RckStr]

haha, Ive been at that site before so I know what you mean. Ill rather just take your word for it :-)

[jumpcuts]

Hello,

I did some test with advancedsettings.xml and <skiploopfilter> 32 completely removes all the jerks on heavy scenes, however Plex's <skiploopfilter> is at 0...

Could it be something else?

Thanks for your time.

[althekiller]

It's not impossible for them to have modified the value in code. I don't keep track of their development. Another possibility is a regression in ffmpeg, though I'm sure I'd have heard davilla swearing about that by now.

[davilla]

Last time I checked, plex's three settings relate to AVDISCARD_DEFAULT, AVDISCARD_BIDIR, and AVDISCARD_ALL.

AVDISCARD_NONE =-16, // discard nothing
AVDISCARD_DEFAULT= 0, // discard useless packets like 0 size packets in avi
AVDISCARD_NONREF = 8, // discard all non reference
AVDISCARD_BIDIR = 16, // discard all bidirectional frames
AVDISCARD_NONKEY = 32, // discard all frames except keyframes
AVDISCARD_ALL = 48, // discard all

Not sure which ffmpeg version they are using. It's sort of hard to tell.

[dteirney]

Those certainly aren't helping you, could be an encoding problem on makemkv's end or demux problem on ours. Perhaps you could provide a small sample that reproduces the issue?

Your system is quite weak to be decoding high bitrate 1080p h264 video. Odds are plex has skip_loop_filter set very high which improves performance at a cost of quality. You can play with it in XBMC via advancedsettings.xml. The wiki is your friend should you chose that route.

I get tons of those errors in my log for DVB-T h264 mpegts playback. Doesn't seem to mean anything based on my playback experience over the last 18 months. That said I'm running a dual core 3.0Ghz Athlon with full software decoding (still on ATI) and I need to set the skiploopfilter to 48 for smooth playback.

[jumpcuts]

Not sure which ffmpeg version they are using. It's sort of hard to tell.

This reminds me of something. When ffmpeg 0.5 came out Plex users experienced playback problem with 1080p mkv, and if I remember well they reverted to a previous version of the VC-1 codecs that used 20% less memory...

[spiff]

i doubt they did. i bet they grabbed OUR code to do the same (which yes, is still in place). in either case this file is h.264, not vc-1.