AppleTV 2 (black) Light Stutter but CPU:~50% FPS:24

ImpreZa · 2012-05-03 22:35

damn you!

**davilla** · 2012-05-04 02:41

...

roma · 2012-05-20 20:30

I read the above. But why is the stuttering less visible (or absent) in the standard ATV Media Player? it seems playback on scenes with a lot of camera movement is much smoother in that player.

**Memphiz** · 2012-05-20 23:25

because apple knows its hardware much better then we do...

thowi · 2012-05-31 22:07

I have the same issue and also checked the CPU while watching the video.
As comparison I watched several trailers directly from the ATV, and they are smooth like butter.
Just when watching from XBMC there is an occasional hiccup every couple of seconds.
It's not consistently at the same part in the video, but more random.

I tried to increase the priority of the AppleTV process (renice -19 -p XXXX) but it didn't make a difference.

Another thing I'm surprised about: Why does it take "so much" CPU anyway?
When watching e.g. the trailers the CPU is 90% idle, with mediaserverd consuming about 8-9%.
Is it all rendered in software, without hardware acceleration?

Most of my videos are H264, so in theory the decoding should be hardware accelerated, no?

Specs of the video I'm using to test this (obtained using http://mediainfo.sourceforge.net/):

Quote:General
Unique ID : 178078051617024349341823972739750109194 (0x85F895CFFA43E1B9A3669FCED1BD200A)
Complete name : /Volumes/data/video/movies/2010 - Tron Legacy/Tron.Legacy.2010.BluRay.720p.DTS.x264-CHD.mkv
Format : Matroska
Format version : Version 2
File size : 6.54 GiB
Duration : 2h 5mn
Overall bit rate : 7 476 Kbps
Encoded date : UTC 2011-03-01 01:21:24
Writing application : mkvmerge v3.2.0 ('Beginnings') 编译于 Feb 12 2010 16:46:17
Writing library : libebml v0.7.9 + libmatroska v0.8.1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 9 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 2h 5mn
Bit rate : 5 965 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.270
Stream size : 5.09 GiB (78%)
Writing library : x264 core 114 r1900 60ef1f8
Encoding settings : cabac=1 / ref=9 / deblock=1:-3:-3 / analyse=0x3:0x113 / me=umh / subme=10 / psy=1 / psy_rd=1.10:0.15 / mixed_ref=1 / me_range=32 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=2 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-2 / threads=6 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=6 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=2pass / mbtree=1 / bitrate=5965 / ratetol=1.0 / qcomp=0.60 / qpmin=1 / qpmax=63 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=40000 / vbv_bufsize=30000 / nal_hrd=none / ip_ratio=1.40 / aq=1:0.80
Language : English
Default : Yes
Forced : Yes

Audio
ID : 2
Format : DTS
Format/Info : Digital Theater Systems
Codec ID : A_DTS
Duration : 2h 5mn
Bit rate mode : Constant
Bit rate : 1 510 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Compression mode : Lossy
Stream size : 1.32 GiB (20%)
Title : English DTS-HDMA core 5.1 1509Kbps
Language : English
Default : Yes
Forced : Yes

I'm using a wired connection.

But I'm seeing this basically with any video that I play, 720p, 1080p, standard definition...

Those hiccups are *really* annoying and (at least for me) ruin the whole experience.

(Oh, and even though I sound like I'm just complaining, I really love XBMC, even donated some money for the awesome work)

thowi · 2012-05-31 23:22

More data:

Tried two movies that I streamed to the ATV using Home Sharing.
They actually also hiccup sometimes.
But they do hiccup more when playing from XBMC, especially when the pictures change more, e.g. when one scene fades into another one.

But when streaming from iTunes the CPU is 65% idle (6% AppleTV, 16% mediaserverd).

When watching the same movies through XBMC the CPU is only 42% idle (~50% AppleTV, 2% mediaserverd).

For comparison I bought aTV (black) and CPU usage is also much lower at 65% idle (27% AppleTV, 2% mediaserverd).
It also has a hiccup occasionally, but less often than XBMC. I think it's comparable to iTunes streaming.

Could this be a spike in CPU utilization, running out of pre-rendered buffered frames?
Are there any background processes in XBMC that consume extra CPU? Missing hardware acceleration?

Possibly this is gonna be better on the ATV3 (more RAM, A5 chip), but it's not jailbroken yet, plus I still want to use my AV2 Smile

ImpreZa Junior Member Posts: 30 Joined: Mar 2005 Reputation: 0 Location: Sweden	2012-05-03 22:35 Post: #11 damn you!
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davilla Team-XBMC Developer Posts: 10,397 Joined: Feb 2008 Reputation: 58	2012-05-04 02:41 Post: #12 ... MediaInfo : http://mediainfo.sourceforge.net/ Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
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roma Junior Member Posts: 5 Joined: Feb 2012 Reputation: 0	2012-05-20 20:30 Post: #13 I read the above. But why is the stuttering less visible (or absent) in the standard ATV Media Player? it seems playback on scenes with a lot of camera movement is much smoother in that player.
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Memphiz Team-XBMC Developer Posts: 7,665 Joined: Feb 2011 Reputation: 91 Location: germany	2012-05-20 23:25 Post: #14 because apple knows its hardware much better then we do... AppleTV2/iPhone/iPod: HowTo find debug logs and everything else which the devs like so much: click here HowTo setup NFS for XBMC: Wiki NFS HowTo configure avahi (zeroconf): Wiki Avahi READ THE IOS FAQ!: iOS FAQ (This post was last modified: 2012-05-20 23:25 by Memphiz.)
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