[MEncoder-users] Important News for iPod/iPhone/Quicktime Encoding

[Alexander Strange]

On Tue, Jun 29, 2010 at 5:06 AM, James Hastings-Trew <jimht at shaw.ca> wrote:
>  On 10-06-29 5:16 AM, - wrote:
>>
>> iPod and iPhone OS 4, and possibly Apple's new Quicktime X, can no longer
>> handle ANY B frames in h264 mp4 videos. [?]
>>
>>  This is CONTRARY to recent mencoder documentation that many of you will
>> have.
>>
>> This may apply for other MPEG-4 standards, but I haven't tried them yet.
>> Seems stupid that they should wander further from the specifications with
>> an
>> upgrade, but there it is-over-priced proprietry software. So,
>> unfortunately,
>> file sizes will increase a bit.
>
> Video files destined for the Apple TV, ipod, ipod touch, iphone, and ipad
> have never tolerated b-frames. They also use a fairly low-spec idc level of
> 3.1. AFAIK this has not changed. These devices are low-power, low-memory
> devices. More "expensive" encoder tricks such as CABAC, b-frames, and mixed
> reference frames all require more memory, and are inappropriate for devices
> of this kind. Every video I have encoded for Apple equipment still plays
> fine after the update to IOS 4.

AppleTV is just a slow CPU running some early version of QuickTime 7,
so it supports everything. (Note there are some bugs in that version,
so x264 weightp and b-pyramid won't work.)
3GS and higher also support High at 3.0 just fine, and iTunes even lets
you sync it.

Try this in the browser:
http://astrange.ithinksw.net/x264/lain_op_high_weight.mp4

If you have problems with some files that should work, try remuxing
them in ffmpeg or mkvmerge+ffmpeg, then check the level you used. (And
then file a bug at bugreport.apple.com.)