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Full Version: Some videos play jerky, others fine - all 720p
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Just installed the latest version of XBMC on a fresh install of 10.6.7 on a Macmini. Previously I was running 10.5 and a slightly older version of XBMC, and it worked flawlessly on the same videos. I only upgraded due to a new hard drive.

Some 720p videos play perfectly, while others exhibit an odd behavior - they'll play, speed up slightly, then play again normally, and they repeat this continuously. Audio always stays the same. CPU never goes above 30% regardless of which video is playing - working or not.

Any clues?
debug log please
VDADecoder Codec failed to open, status(-12470), profile(100), level(31)

The file you are trying to play does not conform to h264 specs and therefor cannot be hardware accelerated

Q2: What are Scene MKV files.

A1: Downloaded HD 1080p files come in all sorts and sizes. This guide will only handle files with these conditions:

1: Use the h264/x264/AVC codec
2: Use DTS or AC3 audio
3: Have maximum codec profile of [email protected]
4: Play these files from the local HD and do not play them using SMB while testing!

1: only h264/x264/AVC files are able to be decoded with VDA the hardware decoder supplied with the mac mini. To my knowledge, VC1 and MPEG are not supported in hardware decoding with VDA.
2: I don't own a DTS-HD or MA receiver
3: When using VDA on the Mac (Mini) only files that fall in the official H264 specs will play correct.

The peak/max bitrate one of those conditions.http://en.wikipedia.org/wiki/H264#Levels. Use Mediainfo Mac to see the profile of the file http://mediainfo.massanti.com/ This means no extreme bitrates or too many reference frames. Please note that the average bitrate is not important. The peaks are. If in a scene the peak bitrate jumps to above 30-40Mbit there could be trouble and frames could be dropped. So when reading scene NFO-files, the average number does not say much. The KillaSample is an example of such a file. It is out of specs and will not play smooth in most hardware decoders and therefore is useless.

For example, for an HDTV picture that is 1920 samples wide (PicWidthInMbs = 120) and 1080 samples high (FrameHeightInMbs = 68), a Level 4 decoder has a maximum DPB storage capacity of Floor(32768/(120*68)) = 4 frames (or 8 fields) when encoded with minimal cropping parameter values. Thus, the value 4 is shown in parentheses in the table above in the right column of the row for Level 4 with the frame size 1920×1080.
( Wikipedia )

Files outside these specs will fail to play smooth. However most current scene files are within these specs. Early HD files may not. Use Mediainfo Mac to check

please post a mediainfo of the played file(s)

and Read this post:
My Macmini is from 2006 and doesn't have hardware acceleration. I turned it off in the settings but playback was the same on this file.

The important thing to note is that this exact file played fine in 10.5 with Atlantis.

Here's the Mediainfo on one of the files in question:


Format : Matroska
File size : 1.09 GiB
Duration : 41mn 31s
Overall bit rate : 3 767 Kbps
Encoded date : UTC 2010-02-22 21:41:29
Writing application : no_variable_data
Writing library : no_variable_data
Video ID : 2
Format : AVC
Format/Info : Advanced Video Codec
Format profile : [email protected]
Format settings, CABAC : Yes
Format settings, ReFrames : 5 frames
Muxing mode : Container [email protected]
Duration : 41mn 31s
Bit rate : 3 317 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate : 29.970 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.120
Stream size : 964 MiB (86%)
Writing library : x264 core 85 r1442tw
Encoding settings : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x113 / me=umh / subme=8 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / sliced_threads=0 / nr=0 / decimate=1 / mbaff=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / wpredb=1 / wpredp=2 / keyint=240 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=2pass / mbtree=1 / bitrate=3317 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00
Language : English


ID : 1
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Codec ID : A_AC3
Duration : 41mn 31s
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 133 MiB (12%)