Generally speaking, for the best video quality and playback the width and height dimensions of the video frame sizes should be a multiple of 16 (best), 8 (better), or 4 (good). This applies to Video On Demand as well as Live streaming.
If you are pushing a live stream using Adobe Flash Media Encoder for use with iOS devices we suggest using frame sizes of 640 x 360 or 480 x 272 for 16:9 aspect ratio. For 4:3 we recommend 640 x 480 or 480 x 360. The video (deinterlaced) should be H.264 baseline level 3.0 to cover the most devices along with AAC audio and not MP3. Key Frame every 1 or 2 seconds. For lower bit rates use a frame rate of 15. N.B: A delay in playback is normal with iPad and iPhone. Apple recommend that an audio sample rate of 22.05 kHz and audio bit rate of 40 kbps is recommended in all cases. We find results are good with bit rates up to 64 kbps, 44.1 or 48 kHz provided that this is not more than 10% of the video bit rate .
The tables below are the video frame sizes settings recommended by Apple who require the video width to be 480 or 640:
Connection |
Dimensions |
Total bit rate |
Video bit rate |
Keyframes |
---|---|---|---|---|
Cellular |
480 x 320 |
64 kpbs |
audio only |
none |
Cellular |
480 x 224 |
150 kpbs |
110 kbps |
30 |
Cellular |
480 x 224 |
240 kpbs |
200 kbps |
45 |
Cellular |
480 x 224 |
440 kpbs |
400 kbps |
90 |
WiFi |
640 x 360 |
640 kpbs |
600 kbps |
90 |
Connection |
Dimensions |
Total bit rate |
Video bit rate |
Keyframes |
---|---|---|---|---|
Cellular |
480 x 320 |
64 kpbs |
audio only |
none |
Cellular |
480 x 300 |
150 kpbs |
110 kbps |
30 |
Cellular |
480 x 300 |
240 kpbs |
200 kbps |
45 |
Cellular |
480 x 300 |
440 kpbs |
400 kbps |
90 |
WiFi |
640 x 480 |
640 kpbs |
600 kbps |
90 |
Connection |
Dimensions |
Total bit rate |
Video bit rate |
Keyframes |
---|---|---|---|---|
WiFi |
640 x 360 |
1240 kpbs |
1200 kbps |
90 |
WiFi |
960 x 540 |
1840 kpbs |
1800 kbps |
90 |
WiFi |
1280 x 720 |
2540 kpbs |
1500 kbps |
90 |
WiFi |
1280 x 720 |
4540 kpbs |
4500 kbps |
90 |
Connection |
Dimensions |
Total bit rate |
Video bit rate |
Keyframes |
---|---|---|---|---|
WiFi |
640 x 480 |
1240 kpbs |
1200 kbps |
90 |
WiFi |
960 x 720 |
1840 kpbs |
1800 kbps |
90 |
WiFi |
960 x 720 |
2540 kpbs |
2500 kbps |
90 |
WiFi |
1280 x 960 |
4540 kpbs |
4500 kbps |
90 |
For further information about video frame sizes see also:
Multi Protocol Streaming Delivery
Mobile Streaming Troubleshooting