iPhone video has a strange FPS.

Question

iPhone video has a strange FPS.

There has been a lot written about "choppy playback" of iPhone video once it's trasferred to another device. It seems to me that the problem is in the frame rate used in the original video. In Quicktime, I'm seeing an actual frame rate on playback of something like 18 FPS, when the file is stamped with 30 FPS. When will this issue be resolved by Apple? And for now, what is the best work around? I've already begun experimenting with different settings during export from Quicktime. Choosing iPhone as a setting creates a .m4v file, but the image size is greatly reduced, and the conversion is very time consuming. Howeber the frame rate issue seems to be resolved--no more choppy playback and the new file is playing back at a true 30 FPS (or maybe it's 29.97 but that's another topic).

It's been said before but I'll say it again: it's beyond belief that Apple can release hardware and software that is this buggy! Even for the most novice user, this is totally unacceptable. They love to say "it just works". Well it doesn't.

Anyone with me on this?

Peter

iPhone 4S, iOS 5.1

Posted on May 3, 2012 1:19 AM

Reply

Answer 1

May 6, 2012 10:45 AM in response to Peter Carlstedt

Have you figured out how to tranfer your videos from your Iphone 4s to you pc without having this problem? I am wasting my time trying to fix this issue, any help thanks

Reply

Answer 2

May 6, 2012 7:16 PM in response to Geovanni68

I wish there was some solution that could be implemented during the transfer. So far I'm only able to fix the frame rate problem by converting the file after I've it's on my laptop. It's very timeconsuming, and the picture quality is lower than the original. Hoping somebody will jump in here with a real solution.

Reply

Answer 3

May 10, 2012 9:10 AM in response to Peter Carlstedt

So far my best solution has been to import the jumpy video into Picasa, where it plays better but still jumpy. Then export it out of Picasa (the export settings seem to be not adjustable--not sure) and then it seems to be 99% fixed. Maybe still a little jumpy, but the image quality and resolution seem as good as the original. And the export renders very fast. I still wish this problem didn't exist to begin with.

Incidentally, some have said these iPhone video files play better in VLC. For me, they would almost not play at all in VLC.

Reply

Answer 4

May 10, 2012 10:24 AM in response to Peter Carlstedt

The video is actually 30 fps. Specifically, the iPhone video is 720p @ 30 fps with h.264 compression and AAC audio with a bitrate of about 11 Mbps. There should be no issues with playback on Apple hardware, and on non-Apple hardware, as long as you are using a platform that has MPEG-4 hardware decoding (and software that supports it).

If you are using a system that doesn't include hardware MPEG-4 decoding, then the CPU needs to do it, and the bitrate is greatly reduced (fps decreases), further, if the computer is under load (lots of other things runnng concurrently) that may happen to.

When you move the video to something like Picasa, it's down-sampled to a lower bit rate so that you can stream it reasonably well. The lower bitrate will make the video easier to playback on under-powered hardware. Other phones address the problem by decreasing the level of compression (presuming that the RAM is fast even if the CPU is not as powerful).

This isn't an issue with the phone, or the format itself per se, but a sort of generic issue with HD video formats: they require considerable resources to encode and decode - so much so that most things employ dedicated hardware for this purpose (which often determines why a particular piece of hardware prefers a particular video format).

If you continue to have issues, you might consider transcoding the video to a lower bitrate so that it works better with your hardware (or upgrade the hardware).

Reply

Answer 5

May 10, 2012 7:50 PM in response to J D McIninch

Thanks for your response JD. How can I tell if my MacBook Pro includes hardware MPEG-4 decoding? My MBP specs are:

Model Name: MacBook Pro

Model Identifier: MacBookPro5,2

Processor Name: Intel Core 2 Duo

Processor Speed: 2.8 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 6 MB

Memory: 4 GB

Bus Speed: 1.07 GHz

Boot ROM Version: MBP52.008E.B05

SMC Version (system): 1.42f4

Serial Number (system): W892518Q91T

Hardware UUID: 14CDAEBD-197D-58FD-B89C-70DEDC7BA917

Sudden Motion Sensor:

State: Enabled

NVIDIA GeForce 9600M GT:

Chipset Model: NVIDIA GeForce 9600M GT

Type: Display

Bus: PCIe

PCIe Lane Width: x16

VRAM (Total): 512 MB

Vendor: NVIDIA (0x10de)

Device ID: 0x0647

Revision ID: 0x00a1

ROM Revision: 3436

gMux Version: 1.7.10

Displays:

Color LCD:

Resolution: 1920 x 1200

Depth: 32-Bit Color

Core Image: Hardware Accelerated

Main Display: Yes

Mirror: Off

Online: Yes

Quartz Extreme: Supported

Built-In: Yes

AFIK, this is all fairly late model Apple hardware and was top of the line when I bought it 3 years ago. Also keep in mind I don't have any issues playing back any other HD content. Only files created on the iPhone 4s.

It doesn't matter if I have other apps running or not--the symptom persists.

I've observed two seemingly identical video files created on my iPhone 4s (using Get Info in Quicktime all parameters are equal) where one plays smoothly and one has the jumpiness. Other times a file that had been playing smoothly starts acting jumpy again after reopening. Bear in mind, the jumpiness doesn't behave like a CPU being overloaded, but is a very regular rhythm--about a jump every second. I would expect an overloaded CPU to produce more random symptoms during playback. I'm now seeing the jumpiness even in the videos I exported using Picasa. Keep in mind, I did not "upload to Picasa Web Albums" but just exported to another location on my internal hard disk. The specs on the exported files look the same as the original including the data rate, which is 21.7 mbits/sec. In other words, they were not optimized for streaming. Why they played back smoothly before and not now is baffling.

Some have speculated that movies created with the camera upside down maybe have some extra data attached in order to play back in the correct orientation. However in most cases my problem files were recorded "right side up" and still they have the jerkiness upon playback.

Finally, you state that 720p is the default iPhone image size but these files appear to be 1080 (progressive or interlaced I don't know). Isn't that what 1920 x 1080 implies? And again, the data rate is 21.7 mbits (is that the same as the bitrate, which you said should be 11 Mbps?).

Your help in this matter is greatly appreciated.

Reply

Answer 6

May 10, 2012 8:09 PM in response to J D McIninch

update:

I found an HDMI/mini display port cable to connect my Samsung HDTV to my MBP. When the Samsung is connected, all video plays back flawlessly on both the Samsung and the Mac display. I can't get it to jump or even hiccup. Seems the Samsung is somehow taking the load off of the MBP's cpu. What exactly is taking place? Please advise.

Reply

Answer 7

Jun 3, 2012 7:01 AM in response to Peter Carlstedt

yes. just transferred several videos from an iphone4 to my sony vaio laptop running windows xp. i am using the latest version of quicktime and the videos DO NOT work.

conversely, i have uploaded to youtube and they seem to be ok when viewed there.

i presume apple is working on an update to quicktime for this?

Reply

Answer 8

Aug 16, 2012 7:06 AM in response to Peter Carlstedt

This did not solve the issues I am having but have you tried using MPEG Streamclip to convert your files? I converted mine over to Apple Pro Res 422 so I could edit my footage in Final Cut Pro. Once in FCP is where I noticed that some of my clips were 29.97 and some were 24.98....

Reply