Podcast video: mp4 vs. m4v vs. ?

Question

Level 1

11 points

Podcast video: mp4 vs. m4v vs. ?

I'm looking for advice whether or when to use m4v vs. mp4 -- or for that matter, a .mov using H.264 -- for a video podcast. Which will be the most universally accessible? Which will supply best performance/download times? Is there really much difference? What I read, even from Apple, seems contradictory and confusing. If you follow one of Apple's tutorials (Creating Video for Ipod) they'll tell you to choose "Movie to Ipod (320x240)" to create video for a podcast. But when I export from QuickTime pro 7.1.3, there is no option to control movie height and width when choosing "Movie to Ipod"; in fact, the Options button is grayed-out. And, if one is starting with a DV file that's 720 x 480 and 30 fps, one ends up with a m4v file that's also 720 x 480 -- at least that's what happened to me. One could work around that by exporting 720 x 480 at 320 x 240 first, but that's pretty clunky. What is the best format? And what about data rate --exporting as mp4 or mov at least let's you select it, not so with "Movie to Ipod." Is there a preferred data rate for podcasts? And is there really any reason to use "Movie to Ipod?" at all?

Powerbook Mac OS X (10.4.8)

Posted on Jan 15, 2007 8:27 AM

Reply

Answer 1

Dr Greg

Level 2

450 points

Jan 15, 2007 10:32 AM in response to webalias rex

Hope I can explain this clearly, as there's a number of issues.

The files with a suffix .mp4 or .m4v are identical (MPEG-4 video), the .m4v is a different suffix so that it's associated with iTunes instead of QuickTime Player.

For a podcast, MPEG-4 would have the most compatibility. For playing on an iPod there are a limited set of settings that will work, which is why exporting Movie to iPod is the most reliable. I would have expected that a file bigger than 640x480 would be scaled down to this size as this is the new biggest size that video iPods can play.

Hope this helps,
Greg

Reply

Answer 2

webalias rex Author

Level 1

11 points

Jan 15, 2007 12:04 PM in response to Dr Greg

Thanks. Helpful advice -- but actually, it raises a few more questions, since you mention that "For playing on an ipod there are a limited number of settings that will work." I'd like more info about that. Tell me if I'm not thinking clearly here: But if I create a video podcast (as I've done experimentally on my .mac site), the video file will available to those who want to click and subscribe and get access via Itunes, courtesy of my xml file -- as well as to those who just want to visit my web page and view the video as they might any other video on the web. That being the case, I'd like to use the smallest file size I can get away with, so that folks can start watching my video asap. Through trial and error, I've come up with some settings that I typically use on web pages that seem like good compromises to me, for various kinds of material (I'll usually start with the default "Movie to QuickTime movie" broadband medium or low settings for H.264, then customize a bit, reducing the data rate until I consider the results unacceptable). The point is, I want to be able to make the trade-offs -- choosing the size, frame rate, data rate, etc. -- that make the most sense for a particular clip, depending on if it has a lot of motion, how important the audio is, etc. Having one "Movie to Ipod" setting with no options doesn’t seem to give me what I need for Itunes/Ipod folks and other web visitors. What settings will -- or won't -- work best in this situation? Is there some information online I've overlooked? Can I get away with one file for web and itunes folks, or am I best off letting "Movie to Ipod" create a file for Itunes, and creating a separate file optimized for the web (either progressive download or streaming, as I have access to a Darwin streaming server.)

Hope I can explain this clearly, as there's a number
of issues.

The files with a suffix .mp4 or .m4v are identical
(MPEG-4 video), the .m4v is a different suffix so
that it's associated with iTunes instead of QuickTime
Player.

For a podcast, MPEG-4 would have the most
compatibility. For playing on an iPod there are a
limited set of settings that will work, which is why
exporting Movie to iPod is the most reliable. I would
have expected that a file bigger than 640x480 would
be scaled down to this size as this is the new
biggest size that video iPods can play.

Hope this helps,
Greg

Powerbook Mac OS X (10.4.8)

Reply

Answer 3

Dr Greg

Level 2

450 points

Jan 15, 2007 1:53 PM in response to webalias rex

This page has all the info about the formats supported by the video iPod: http://www.apple.com/ipod/specs.html

Reply

Answer 4

Jan 21, 2007 9:49 AM in response to webalias rex

For all intents and purposes - mp4 and m4v are the same. There are a few annoying differences with how iTunes handles them though.

When you access your podcast through the iTunes store - and see your main Podcast display... If you double click on the episode - m4v will begin streaming it ASAP. MP4 does nothing. You need to go to the "Get" screen to actually play the file.

Not a huge difference - but a lot of our users have been confused by it.

Reply