[APPLE TV] XBMC on Apple TV (720p) H.264 video bit-rates?

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davilla Offline
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Post: #16
yea, I'm waffling on that now. More comparisons seem to indicate that quicktime on the AppleTV knows a similar trick as the skip-loop-filer settings under ffmpeg. If quicktime on the AppleTV is using the GPU for h.264 decode assistance, it's difficult to determine without diving deep into the quicktime/nvidia driver code.


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Carniphage Offline
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Post: #17
I can't find anything definitive on hardware assist on the AppleTV either way.

I guess the cheap-ass solution would be to play MP4s and MOVs using Quicktime itself. No need to reverse engineer nothing!

C.
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babanoosh Offline
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Post: #18
Sufficed to say that the Apple TV cannot play x264 endcoded bluray/hddvd rips (mkvs) at 720p w/o reencode to mp4 container (or transfer to .ts with aforementioned tool); making sure the bitrate is below 5000kbps; and it's finicky with DTS... does that about sum it up?

What would be the de facto level and profile of most x264/DTS or DD matroska material these days... is it Level 4 HiP?

TIA!
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danyg Offline
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Post: #19
I tried Handbrake, but with a lot of files it simply crashes...
I don't know why ...

Does anyone suggest any good software to re-encode mkvs to atv ?

Thanks/Dany
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VonMagnum Offline
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Post: #20
I'm currently trying to find a happy medium in the public SVN 2592 build of Handbrake to build AppleTV compatible MKV movies with DTS for my DTS DVDs that have no 5.1 Dolby Digital tracks on them (e.g. Jurassic Park, Daylight, etc. and even some music videos by Tori Amos that only have 5.1 in DTS). What I'm finding is that Handbrake's constant quality setting (ranging from 57-60 depending on the build of Handbrake) switched to MKV are not working well at all. It stutters every 5-10 seconds. These same settings work fine for M4V on Apple's own software. I'm now trying to find a constant bit-rate setting to use instead. I'm lowering down to 56 on constant quality and trying out 5500 on average bit-rate to start. But if anyone knows of a good setting for XBMC and/or Boxee on AppleTV to do MKV DTS video with, I'd like to hear about it. These are just standard definition. I can't even imagine 720P encoding without burping in XBMC on AppleTV.... XBMC seems to have some kind of color/banding issue on AppleTV as well (doesn't show up in Boxee on ATV or in XBMC on my MBP) that looks lke 16-bit dithering or something similar.
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jmarshall Offline
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Post: #21
@VonMagnum: See my other reply to you in the other thread regarding your banding issues.

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VonMagnum Offline
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Post: #22
jmarshall Wrote:@VonMagnum: See my other reply to you in the other thread regarding your banding issues.

Thanks. I just saw that. I'll play with it tomorrow as it's about time to hit the sack.

Meanwhile, after some testing with several different settings and even my router's broadcast channel to try and figure out why DTS MKV video stutters, I'm still at a bit of a loss. Lowering the bitrate or quality settings for a video to encode in Handbrake does not stop the stuttering (just makes the picture worse). The weird thing is that if I encode multiple audio tracks (the rest non-DTS) and switch to a different audio track, the stuttering problem disappears and the video plays back normally. This occurs with both XBMC and Boxee (I am streaming both over SMB shares).

However, in Boxee, it shows a dual-color progress indicator and it's clear that it's buffering a certain amount ahead of where it's playing and will only load as it goes (it does not attempt to keep loading/storing the video on the hard drive like something along the lines of an Apple movie rental would do). But the difference I see when using a DTS audio track versus a non-DTS track is that with the non-DTS tracks it seems to more or less keep pace a certain distance ahead of the playback point on the graph, but with DTS selected, it will load a certain distance ahead (grey bar) and then the playback point (yellow bar) will almost, but not quite catch up with it and then all the sudden it loads way ahead on the grey bar and just as it stops loading any further on the grey bar, it stutters and then playback continues and the yellow bar almost catches up and then it loads and just as it stops loading ahead it stutters again at the same pattern over and over. Again, selecting a non-DTS track seems to keep a nice even pace on the buffering.

I have no idea why there's a different pattern there, but the fact the stutters seem to occur just after loading a big buffer seems like whatever is happening isn't some random thing or the WiFi signal going patchy or whatever. I'm curious if others on here are playing back DTS MKV files on their AppleTV units over WiFi and if so whether they are having any stutter/pause/buffer issues with them. They seem fairly consistent here regardless of bit-rate settings, length of feature (even the DTS Trailer which is very short will stutter, usually at the same points each time) or even whether I use XBMC or Boxee. I don't know if there's a hidden setting somewhere that might help. I plan to read the online manual tomorrow and see if there's anything that might help with DTS audio.
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VonMagnum Offline
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Post: #23
I found out what was causing the stutter issues. It was the Airport Express 802.11N network. When I switched to my primary network (Netgear N), all the stutter issues went away. I've heard about Apple network issues before, but these must be very short/brief interruptions/disconnects (Apple's own software ignores them, but XBMC chokes). Everything loads faster with NetGear as well (full video_ts DVDs are only slightly slower changing tracks/chapters over the network than storing them locally). I can now watch DTS movies seemingly without issue. I used to use the NetGear network all the time and used the Apple one for G-devices, but the Netgear router had a tendency to dump over time and require a reset of the router once in awhile that the Apple router never seems to have. Oddly, since not using the Netgear router with the AppleTV units all the time, it seems much more stable itself. Maybe it's the Apple hardware on either end that somehow trips things up. I've had several firmware upgrades for the Airport Express units and apparently none have made any difference since the stutter thing is with the latest firmware.
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pmcd Offline
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Post: #24
hariseta Wrote:To change the MKV container to TS without re-encoding the h.264 I use a tool called tsMuxer. This tool normaly runs on Windows, but I use Darwine to run in on OS X. It is very fast, around 2 minutes for a 1 GB MKV file.

The resulting TS file plays fine on Apple TV. Also I noticed that when the container is MKV and audio track is DTS, the DTS does not play.
The same movie in a TS container will play DTS on the Apple TV.

Now if the H.264 is high-profile even ina TS container the ATV cannot play it correctly. So I guess the bitrate has to be reduced to 5500 kbps.
I have not tried tsMuxer yet to do this, but looks like it is much faster than the other tool I tried (visual hub, handbrake) even running in Darwine.

You demux the mkv file into a video (.ts) file and an audio file (.ac3). Then do you just mux them back in order to play? I assume you would be using nitoTV or ATVFiles or something like that? iTunes won't deal with it or will it?

pmcd
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