At 08:23 2008-04-04, David King wrote:
>Bill - does that size make it back through itunes onto an ipod? I thought
>ipod compatible videos had a smaller kbps cap, like around 6-700?
>
>David
Well that's the very point, apparently not, since firmware 1.2, as long as the
files
are encoded as 'low-complexity' h.264, the limit goes up to 1.5mpbs.
I've finally found some info on
http://developer.apple.com/technotes/tn2007/tn2188.html
which is aimed at application authors wanting to incorporate QTPro
functionality into
their programs.
Only the 'export to iPod' option gives you the 'low complexity' profile, and
that is
only applied to sources that are bigger than 320x240. Sources that are bigger
than 640x480 are scaled to fit. These are the sizes & profiles applied
320x240 or less as source baseline 1.3
>320x240 up to 640x480 as source baseline LC
>640x480 scaled to fit preserving aspect ratio baseline LC
I assume this cures the letterboxing that used to occur when converting NTSC DV
which is why
old-schoolers like me avoided the iPod preset in the first place.
As far as bitrates go:
320 x240 goes at 700kbps
640x480 at 1.5mps
and anything else somewhere between the two according to this formula:
DR = { (nMC * 8 ) / 3 } - 100 where DR is the data rate in kbps and nMC is the
number of macroblocks in the image.
Then comes the bit about 16:9 and I get confused again. Some code is
illustrated to
demonstrate 'aperture modes' After a couple of pics that indicate that
widescreen video will become a little squished on a classic iPod. It says
IMPORTANT: As shown in Table 4, the iPod export component will only scale movie
images larger than 640x480 to fit while maintaining aspect ratio to produce
Baseline Low-Complexity profile .m4v files. If you want to produce Baseline
profile .m4v files up to 320x240 or Baseline Low-Complexity profile files
larger than 320x240 (but smaller than or equal to 640x480), you will need to
correct for aspect ratio yourself.
Could someone explain that, please?
> I use a mac. I don't know it that makes instructions different from a
> PC. I've never clicked anything that says "low complexity". When you
> get to the selection area, "Main" is selected by default. I click
> "Baseline" and that's it. From FCP, for instance:
>
> Export to Mpeg4
> Compression: h.264
> 640x360
> 1400 kbps
> 30 fps (or 24, depending)
> Select "Baseline"
Bill, I always understood that that option gives the 1.3 profile, am I wrong?
I take it that you've tested that on an iPod. In which case I must be.
I'll admit that I've never owned one of the b*****rs
Joly
>On Fri, Apr 4, 2008 at 6:28 AM, Bill Cammack <[EMAIL PROTECTED]> wrote:
>
>
>>
>> Also, check out http://www.freevlog.org/ for their tutorials.
>>
>> Bill
>> http://BillCammack.com
>>
>> --- In videoblogging@yahoogroups.com <videoblogging%40yahoogroups.com>,
>> WWWhatsup <[EMAIL PROTECTED]> wrote:
>> >
>> >
>> >
>> > I've been happily using QT Pro on the PC to convert 4:3 DV into
>> iPod-compatible 320x240 baseline
>> > h.264 @ 608kpbs ever since the the first video iPod was introduced.
>> Now I've been persuaded to start
>> > shooting 16:9 and I'm wondering how to best to encode it for iPod. A
>> couple of things puzzle me.
>> >
>> > 1) I note that in the spec
>> http://www.apple.com/itunes/store/podcaststechspecs.html it gives the
>> newer option:
>> > H.264 video, up to 1.5 Mbps, 640 x 480, 30 frames per sec.,
>> Low-Complexity version of the Baseline Profile
>> > with AAC-LC audio up to 160 kbps, 48 Khz, stereo audio in .m4v,
>> .mp4, and .mov file formats
>> >
>> > However the h.264 options in QT Pro only give 'baseline' or 'main'
>> but no 'low-complexity'?
>> >
>> > 2) Googling around I see some mention of 640x352 as being the
>> optimum size for 16:9 - why not 640x360?
>> >
>> > All advice appreciated.
>> >
>> > Thanks
>> >
>> > Joly
>> >
>> > punkcast.com
>> >
>> >
>> > ----------------------------------------------------------
>> > WWWhatsup NYC
>> > http://pinstand.com - http://punkcast.com
>> > ----------------------------------------------------------
>> >
>>
>>
>>
>
>
>
>--
>David King
>davidleeking.com - blog
>http://davidleeking.com/etc - videoblog
>
>
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>
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