H264 maximum bitrate hack

Question

Level 2

150 points

H264 maximum bitrate hack

I don't know if this has been discovered already, but Apple's stated maximum bitrate of 750 kbps for an H264 video stream is bogus. I have my 5G iPod playing up to 1000 kbps so far. Just can't transfer it through iTunes, have to trick the iPod. More to come later, after some sleep.

Posted on Dec 17, 2005 4:39 AM

Reply

Answer 1

Rohan Hill Author

Level 2

150 points

Dec 17, 2005 5:09 AM in response to Rohan Hill

to follow-up, I have 1400 kbps H264 running on my iPod right now.

it won't (as we all know) transfer using itunes. here's the hack/workaround. encode your video to spec (750kbps max H264, etc) and use itunes to transfer it. make note of the file size. open your ipod_control folder on the ipod drive and search for all .mp4 files that are approximately the same size as the file you transfered - this should make it relatively easy to find the final resting spot of the "properly" encoded video file. note the filename, and rename your higher bitrate (i'm up to 1400kbps h264 without any skipping thus far) to the same name. copy it in place of the original "proper" video file, unplug the ipod, and give it a try.

seems like the decompressor chip is capable of a lot more than Apple wants us limited to.

Reply

Answer 2

Jon Walker

Level 6

19,489 points

Dec 17, 2005 5:12 AM in response to Rohan Hill

I don't know if this has been discovered already, but Apple's stated maximum bitrate of 750 kbps for an H264 video stream is bogus. I have my 5G iPod playing up to 1000 kbps so far. Just can't transfer it through iTunes, have to trick the iPod. More to come later, after some sleep.

The stated limitations are likely to be very conservative in order to guarantee playback on the widest range of individual 5G iPods. (Remember the limitations they put on iDVD burning?) In any case, iTunes seems to be the arbiter as to whether or not the file is to be sync'd. So if you are using an application with a different limitation (or no limitation at all) then, yes, the files may sync but may or may not be playable (or play poorly) once on the iPod.

2.0GHZ G5/533MHz G4 DeskTop/400MHz G4 PB Mac OS X (10.4.3)

Reply

Answer 3

moo'

Level 1

15 points

Dec 17, 2005 5:42 AM in response to Rohan Hill

using nero you can easily choose up to 4000kpbs. also these went into itunes just fine and transfered just fine. even played on my ipod just fine. the thing to watch is 4000kpbs looks no different than 750kpbs (or 790 as nero likes ot encode at) seriously try watching your favorite episode of family guy or something at 750 then watch it at however high you can get it and you will see no difference (or very little) i might be blind or just no care but over 750 doesnt matter and is just taking up space.

Now for watching at hon a tv at 320x220 then the 4000 might be noticlbly different but seeing as i own the dvd's to the movies on my ipod i just insert the movie.

I would like someone else to either verify or disprove what i have found though. since i only went by what my eyes can see

Reply

Answer 4

Jon Walker

Level 6

19,489 points

Dec 17, 2005 6:17 AM in response to moo'

Am curious as the the file size and duration in minutes for such files.

2.0GHZ G5/533MHz G4 DeskTop/400MHz G4 PB Mac OS X (10.4.3)

Reply