Best settings for iPad retina display from Full HD

MattAdamson wrote on 12/21/2013, 11:01 AM
All,

I have just purchased a new iPad Air with the retina display which exceeds 1080p and would like to convert all my existing AVCHD M2TS video from my camcorder so I have mobile access to all my favorite family movies.

I wondered if others had this device and what there best settings were. I tried using the MP4 presets for Sony AVC encoding both for 720p and 1080p 30 fps. The 1080p format looked much clearer on the iPads screen however I noticed it appeared to start stuttering a minute or so through. The audio then stopped being in sync e.g. hearing audio a few seconds before the video was due to catch up.

I had this before when rendering for the Sony PS3 and had to use tsMuxer to make sure the FPS was set correctly However the FPS looks correct here in the rendered video and besides tsMuxer supports M2TS muxing which won't then play on the iPad

I couldn't find any obvious posts related to this neither on google. Many indicate using 720p however 1080p does look better if it didn't stutter. Perhaps the iPad doesn't have the processing power? If not perhaps another less compressed format would help

Many thanks

Matt

Comments

pilsburypie wrote on 12/21/2013, 3:48 PM
Sorry I can't offer advice, but I too am in a similar boat. My home movies are shot in 1080 50p and I render them beautifully to mp4 for playback on my TV. I am looking for the optimal setting of quality but with reasonable file size for my iPad air.

Look forward to any advice.
JohnnyRoy wrote on 12/21/2013, 4:21 PM
> Posted by: MattAdamson "I tried using the MP4 presets for Sony AVC encoding both for 720p and 1080p 30 fps. The 1080p format looked much clearer on the iPads screen however I noticed it appeared to start stuttering a minute or so through. The audio then stopped being in sync e.g. hearing audio a few seconds before the video was due to catch up. "

The default bit rate on the Sony AVC 1080p is 16Mbps. That's way more than you need. I'm guessing you could render to 8Mbps and get great quality that won't stutter and stay in sync.

~jr
john_dennis wrote on 12/21/2013, 5:33 PM
Try this. If it works, I'll post the project and render settings.

From Apple's web site:

TV and Video

* Video formats supported: H.264 video up to 1080p, 30 frames per second, High Profile level 4.1 with [I]AAC-LC audio up to 160 Kbps[/I], 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats; Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format
pilsburypie wrote on 12/22/2013, 5:57 AM
John - thanks for posting the clip. It looks very reasonable on my iPad. Not quite as crisp as some of my larger sized files but good all the same. As I said, I'm trying to get a balance between file size and quality. The quality is no issue, but getting a sensible sized file is.

With that quote from the Apple site, I'm a little confused. Sure I understand it can take 1080 mp4, but what is the High profile level 4.1 bit? How comes it gives bit rates for other formats but not the mp4? I suppose this is not relevant as it is giving the "up to" sizes. Probably not what I'm after as I'd want to go smaller.

I was hoping for an answer giving exact settings being a bit lazy, but I suppose I had better get off my bum and do a few test renders myself!

I'll report back.
john_dennis wrote on 12/22/2013, 10:04 AM
"[I]what is the High profile level 4.1 bit?[/I]"

You can learn more than you ever wanted to know about profiles and levels here.

I held the bit rate to 2 mbps even though Apple allows 2.5 mbps. You could push it over their limits if you like to live dangerously.

From the iPad specs, if your source is 50p, you should probably render 25p with no resample. After coffee, I'll post the templates I used.
john_dennis wrote on 12/22/2013, 1:10 PM
Here is a file that I rendered with the Mainconcept AVC render template customized to match Apple's stated requirements as closely as I could. This template began as the original Sony Tablet 1080p template. Individual settings are here.

The file has the following characteristics from MediaInfo:

General
CompleteName : C:\Users\John\Desktop\2013 Nutcracker\iPad Retina Test Mainconcept 2_5 mbps.mp4
Format : MPEG-4
Format_Profile : Base Media / Version 2
CodecID : mp42
FileSize/String : 10.3 MiB
Duration/String : 35s 77ms
OverallBitRate_Mode/String : Variable
OverallBitRate/String : 2 468 Kbps
Encoded_Date : UTC 2013-12-22 18:50:41
Tagged_Date : UTC 2013-12-22 18:50:41

Video
ID/String : 2
Format : AVC
Format/Info : Advanced Video Codec
Format_Profile : High@L4.0
Format_Settings_CABAC/String : Yes
Format_Settings_RefFrames/String : 3 frames
Format_Settings_GOP : M=4, N=15
CodecID : avc1
CodecID/Info : Advanced Video Coding
Duration/String : 35s 77ms
BitRate_Mode/String : Variable
BitRate/String : 2 304 Kbps
BitRate_Maximum/String : 2 500 Kbps
Width/String : 1 920 pixels
Height/String : 1 080 pixels
DisplayAspectRatio/String : 16:9
FrameRate_Mode/String : Constant
FrameRate/String : 23.976 fps
Standard : NTSC
ColorSpace : YUV
ChromaSubsampling : 4:2:0
BitDepth/String : 8 bits
ScanType/String : Progressive
Bits-(Pixel*Frame) : 0.046
StreamSize/String : 9.63 MiB (93%)
Language/String : English
Encoded_Date : UTC 2013-12-22 18:50:41
Tagged_Date : UTC 2013-12-22 18:50:41
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID/String : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format_Profile : LC
CodecID : 40
Duration/String : 35s 29ms
BitRate_Mode/String : Constant
BitRate/String : 160 Kbps
Channel(s)/String : channel0
Channel(s)_Original/String : 2 channels
ChannelPositions : Front: L R
SamplingRate/String : 48.0 KHz
Compression_Mode/String : Lossy
StreamSize/String : 684 KiB (6%)
Language/String : English
Encoded_Date : UTC 2013-12-22 18:50:41
Tagged_Date : UTC 2013-12-22 18:50:41

I am at a slight disadvantage since I don't have an iPad, I'm only attempting to comply to posted specifications. To be honest, my 1280x720-23.976p efforts (Bits/(Pixel*Frame) : 0.104) looked better on my computer screen than the 1080p. I trust that others will come up with something twice as good.

This post passed with very little fanfare, but considering who posted it, I took it to heart.

MattAdamson wrote on 12/22/2013, 2:28 PM
thanks both johns for your feedback.

From JohnnyRoy response

"The default bit rate on the Sony AVC 1080p is 16Mbps. That's way more than you need. I'm guessing you could render to 8Mbps and get great quality that won't stutter and stay in sync."

I actually tried using 8 Mbps and the video played perfectly so this is my best setting yet.

John Dennis I also tried the template above however it looked far worse as expected really at that low bit rate. Perhaps it can go higher than 8 m bits per second however Im not sure I could tell that much difference.

I wanted to find the optimum settings and then do a large batch conversion through Vegas of all my m2ts file using the supplied script. This sounds like a good start
john_dennis wrote on 12/22/2013, 2:35 PM
I was somewhat taken back to see Apple specifying 2.5 mbps. If a higher bit rate works, you can find your own sweet spot between "video quality" and file size.
pilsburypie wrote on 12/23/2013, 8:17 AM
I have done a bit of testing with render settings and feel that the Sony AVC mp4 template can be reduced down to 6mbs for a reasonable file size. For me below 10mbs is where I can start to notice a slight degredation, but as I said, file size is important.

My 1.5 hour family video project comes out a 3.5Gb when using 6mbs which although I'd rather smaller, isn't bad for the fairly decent PQ.

I've also had a play with Handbrake. I have tried a few templates and fiddled with them but can't really seem to get much smaller without affecting PQ. Then again I am a Handbrake novice. Maybe this program may be able to shave off some file size in the right hands.