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

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IT-King Offline
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Post: #1
If anyone experiences the same or has a solution please comment because its driving met nuts Confused

Problem Description:
- I experience weird/light stuttering on ATV2. This is especially noticable when camera's move e.g. left-right/right-left, zoom-outs and flyovers.
- The stutter isnt long

So first things first:
- I enabled the debugging, and to my surprise CPU was around 50% and XBMC FPS:24 constantly.
- File(s) used are mostly *.mp4
* Video Resolution: 720 x 360, Aspect ratio: 2.8082, Format: H264, Bitrate: 1055 kbps,Frames per second: 23.976
* Initial Audio Stream, Format: MP4A, Bitrate:159 kbps, Rate: 48000 Hz, Channels:2
- Networking: Wireless, but i also experience the problem while wired.
- Protocol: SMB but experience the same over NFS.
- Read all related content on stuttering and applied those settings (if its in the wik or on the forumi i've tried it) (disbled sync/16-bit output...etc..etc)
- Installed top "apt-get install top", this shows cpu-usage for all ATV2 processes around 50%.
- Same problem occurs when i copy a part of the movie to ATV2 itself.

[Image: atv2top.png]
(This post was last modified: 2012-04-30 22:14 by IT-King.)
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konaag05 Offline
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Post: #2
I have had stuttering and buffering issues, even with my computer before. I traced this back to my network setup.

I have AT&T Uverse, which uses IP for the TV signal. When any TV streams were operating, the switch in the modem would not have enough bandwidth to also deliver my .mkv stream to XBMC.

To solve this, I added an additional switch and put all non-TV traffic on it.This allowed the external switch to handle the XBMC stream while the modem switch handled the TV. This may not be your issue, but could be similar.
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Memphiz Offline
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Post: #3
it-king - what you describe is the stuttering which is mostly visible during pan scenes when 23.97fps work against 60hz refreshrate. Since it is not possible to change the atv2 output to 24hz refreshrate this is something you have to live with for now...

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
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smitopher Offline
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Post: #4
(2012-05-01 12:45)Memphiz Wrote:  it-king - what you describe is the stuttering which is mostly visible during pan scenes when 23.97fps work against 60hz refreshrate. Since it is not possible to change the atv2 output to 24hz refreshrate this is something you have to live with for now...
I had (and sold) an ATV 3 and I noticed that in the Video settings, they had some video settings for refresh rate, along with the ubiquitous "auto". Do we know at this time whether this is hardware or is this available for ATV 2 with ios 5.1?
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Memphiz Offline
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Post: #5
only 50 and 60hz. Its there for atv2 too since ios 4.4.4. There is no api for switching the refreshrate from within xbmc.

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
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IT-King Offline
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Post: #6
It is also there in 4.4.3, i already had the ouput set to 720p 50hz. It makes no difference.
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ImpreZa Offline
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Post: #7
(2012-05-01 12:45)Memphiz Wrote:  it-king - what you describe is the stuttering which is mostly visible during pan scenes when 23.97fps work against 60hz refreshrate. Since it is not possible to change the atv2 output to 24hz refreshrate this is something you have to live with for now...

This sounds interesting... Big Grin
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Memphiz Offline
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Post: #8
Did i miss type it?

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
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ImpreZa Offline
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Post: #9
I just hoped that you meant something with the dots " for now..."
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Memphiz Offline
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Post: #10
lol ... nope ... i allways use dots ... see? Big Grin

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
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ImpreZa Offline
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Post: #11
damn you! Tongue
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davilla Offline
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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 Offline
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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 Offline
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Posts: 10,139
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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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thowi Offline
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Post: #15
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)
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