Mar 30, 2007

Export To AppleTV specs - MacNN Forums

Export To AppleTV specs - MacNN Forums

Ok, I just tried the "Export to AppleTV" command in QuickTime Pro 7.1.5 and here are the specs of the resulting file:

.m4v extension

H.264 video codec, 640 x 480 (that was my source file), 24fps ( my source was 24fps)
AAC audio codec, 44.1kHz stereo

Overall file bitrate is 2.2Mbps

So we're at the low low end of DVD quality on the bit rate. I had no option to adjust any settings, so I have to wonder if MPEGStreamclip or Handbrake may offer an update soon to allow us to tinker with settings when we convert files.

Overall, good effort by Apple on the preset, but it would be nice to adjust the settings to get more bits for video, and par the audio down to something like 32kHz AAC at 96 or 128kbps.

I haven't tried HD video yet, I will tomorrow to see what it spits out.

Ok, I ran an HD test this morning on the Export to AppleTV command in QuickTime Pro.

My source file was a 19 second DVCPRO HD file, 720p, 23.98fps. DVCPRO HD stores files at a resolution of 960x720, and when you play them back, QuickTime Player shapes it at 1248x702 to get the aspect ratio correct.

I ran the exporter, and what I got was a .m4v file. Video was using H.264, at a size of 1248x702, at 23.98fps. Data rate on the video track is 4.85Mbps. Audio was AAC, 44kHz stereo, at 128kbps. That puts the whole file at 4.9Mbps, just under the maximum AppleTV spec data rate of 5Mbps (according to the Apple website)

So it appears that the basic QuickTime exporter does a great job of maximizing available data bandwidth for HD content, when it is given a high quality source such as DVCPRO HD. The resulting video was a bit soft, but most of the detail was there, and I think it would look good on an HD set through the AppleTV.

To update you on the SD test that I did, the video data rate is 2.15Mbps, and the audio was at 128kbps. Not bad, but just at the bottom end of DVD quality. It would be better if the exporter would give standard definition video a higher datarate, such as at least 3.5Mbps, so we could get DVD quality bitrates out of it.

HD results are promising. I'm fairly impressed there.

Let's hope that third parties tie into this exporter, and allow us to up the datarate on video so we can get some better results out of standard definition content.

Overall, I'm fairly impressed.

I was using a G4 MacMini for the exports. I would definitely get an Intel Mini or iMac for all exports. You will have much better export times.

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