Jerky video playback on iOS devices with Cupertino streaming

[cherdt]

We are streaming h.264-encoded .mov files using both rtmp and Cupertino streaming.

Playback of the files on an iOS device using Cupertino streaming is jerky (although the audio is smooth). Here's an example:
http://www.law.upenn.edu/cf/newsroom...Democracy.html

The files were encoded using Compressor (part of Final Cut Pro) with the Frame Reordering option selected. It appears that when we re-encode the video without Frame Reordering, playback is smooth.

Is this functioning as designed? I want to make certain there's not a Wowza setting we can adjust that will address the issue before we start the process of re-encoding all of our videos.

On a side note, our observations indicate that more sites are using .mp4 containers (rather than .mov) and I was wondering if anyone here had an opinion or preference on the matter.

[rrlanham]

I'm seeing same, interesting affect. How was the video encoded exactly?

Richard

[cherdt]

Here are the encoding settings we used:

Description: No description
File Extension: mp4
Estimated file size: 316.39 MB
Audio Encoder

AAC, Mono, 48.000 kHz

Video Encoder

Format: QT
Width: 534
Height: 300
Pixel aspect ratio: Square
Crop: None
Padding: None
Frame rate: 24
Frame Controls On:

Retiming: (Good) Frame Blending
Resize Filter: Linear Filter
Deinterlace Filter: Better (Motion Adaptive)
Adaptive Details: On
Antialias: 0
Detail Level: 0
Field Output: Progressive

Codec Type: H.264
Multi-pass: On, frame reorder: Off
Pixel depth: 24
Spatial quality: 75
Min. Spatial quality: 25
Temporal quality: 50
Min. temporal quality: 25
Average data rate: 0.717 (Mbps)
Maximum data rate: 0.717 (Mbps)
Fast Start: on

[rrlanham]

Encoding for iOS and other mobile devices should be as simple as possiblle. Any of these options that add complexity, deselect them or select the least complex option.

Take a look at the ffmpeg and MS Expression 4 presets for comparison:
http://www.wowzamedia.com/forums/con...ideo-on-Demand

You do not show gop or key frame frequency (gop/fps). It's important to know key frame frequency in iOS, which should be a factor of cupertinoChunkDurationTarget which is 10 seconds by default:
http://www.wowzamedia.com/forums/con...arameters-(iOS)

Richard

[cherdt]

Thanks. We're re-evaluating our encoding settings based on the info you provided.

One other possibly related question: we've noticed a brief (fraction of a second) stutter when first playing video on an iOS device using Cupertino streaming. Here's an example:
http://www.law.upenn.edu/cf/newsroom...CupFinals.html

When I press play, it starts playing, then starts playing again from the beginning.

[rrlanham]

I don't know what that could be, seems like an encoding problem.

However I did not see anything like that when I played in on my IPhone 3gs with iOS 4.3. Plays well, starts quickly, av sync is perfect.

Didn't seem like it was streaming though, progressive download I think

Richard