*.3gp vs *.mp4... difference?

[Elias]

Seriously, when I look in Dumpster I can't see the difference. Both fileformats are very similar. What's the difference between them? Is it safe to have an *.mp4 file and rename it to *.3gp and vice versa? As far as I can tell, *.3gp can hold more codecs, but that's about the only difference I can notice. I'm not even sure if this is a unique ability that *.3gp has over *.mp4 though...

[magicclue]

THE ANSWER IS NEAR! (http://www.fuckinggoogleit.com/)

:D

[magicclue]

You're right. These containers are the same.

One exception: MP4 uses AAC for audio while 3GPP uses AMR (adaptive multi rate). 3GPP has chosen AMR because mobile phones are already transmitting calls via AMR.

[Elias]

Is it safe to have an *.mp4 file and rename it to *.3gp and vice versa? I never use amr or any other non MPEG-4 codecs.

[Drachir]

As far as I know 3gp files can(should only) store Mpeg4 SP,H263 video and aac or amr audio. Not sure about AVC/H264 and HE-aac for the moment.

MP4 files can store Mpeg1/2 video, Mpeg4 ASP, AVC/H264 and (HE)aac and mpeg 1 Layer II/III (list of possible media types http://gpac.sourceforge.net/tutorial/mediatypes.htm ).

3GP files have no IOD or BIFS/OD track.

This systems tracks are needed for interactivity and more complex presentation in MP4 files. Here you can find a sample with javascript: http://www.comelec.enst.fr/osmo4/mp4/othello.mp4

Most players deal with 3GP and MP4 files the same way. From this point of view it is save to rename a MP4 file to 3GP or vice versa.
But it is not the right extanton. Your are right there is not much difference between 3GP and MP4 files especially if they where created with a program like mp4muxer and include more than on audio stream. This files will only have an empty IOD and no BIFS/OD track if the frontend use MP4Box to create the MP4 file. If it use mp4creator the scene will be b0rked. It will have a scene only suitable for a MP4 file with one audio/video track. I never used mp4muxer so i am not sure but you can test is with MP4Box -info mp4muxer.mp4 and MP4Box -bt mp4muxer.mp4.

[Elias]

Originally posted by Drachir
As far as I know 3gp files can(should only) store Mpeg4 SP,H263 video and aac or amr audio. Not sure about AVC/H264 and HE-aac for the moment.

MP4 files can store Mpeg1/2 video, Mpeg4 ASP, AVC/H264 and (HE)aac and mpeg 1 Layer II/III (list of possible media types http://gpac.sourceforge.net/tutorial/mediatypes.htm ).What about 3GPP Timed Text? Can *.mp4 store that in full compliance with the MPEG-4 ISO/IEC standard, or is it some kind of a hack/modification like VBR *.mp3 in *.avi?

[magicclue]

well, an Apple Quicktime developer answered a similar question "quoted" straight forward:


I have search the net a lot of time but failed to gather detailed information about the container format for .3gp or .3g2 file. Is therer any one please help me giving information about the container format and the internal format of .3g2 and .3gp file such as header description ..etc.
thanks for co-operation and help...
Total Posts: 3 | Joined June 2004 | Posted on: 4:56 pm on June 23, 2004 | IP
hansjuergen


"On the tech mailing list of MPEGIF there has been an answer from an Apple developer to a similar question yesterday:"

"At 12:36 PM +0530 6/1/04, rchawla wrote:

> Is a file writer reference software available on the net which
> can save MPEG4 video+AMR audio in a .mp4 file?

well, AMR isn't strictly an MPEG-4 codec, so QuickTime will save this only in a .3GP file (which happens to be structurally the same as MP4 for all intents and purposes).
--
David Singer
Apple Computer/QuickTime"

[zwommie]

Originally posted by Elias
What about 3GPP Timed Text? Can *.mp4 store that in full compliance with the MPEG-4 ISO/IEC standard, or is it some kind of a hack/modification like VBR *.mp3 in *.avi?

http://gpac.sourceforge.net/auth_text.php

[bond]

Originally posted by Elias
Is it safe to have an *.mp4 file and rename it to *.3gp and vice versa? I never use amr or any other non MPEG-4 codecs. while most tools might not recognize the difference, strictly speaking you cant rename from .3gp to .mp4 or vice versa

both 3gp and mp4 signal inside the file what "brand" they are (or said in a different way, whether they are mp4 or 3gp) and that will of course not change when you simply rename the extension.
another thing mentioned is the iod, when you rename a .3gp without iod to .mp4, the .mp4 will not be 100% spec compliant as in .mp4 the iod atom is mandatory
i am sure there are lots of other differences too

actually even if many tools might not care about these things (some might) and 3gp and mp4 might be 99% the same, still they are not 100% the same and therefore i would never rename the extension, as changing the extension never changes the format of course
especially as tools like mp4box can make correct conversions from 3gp to mp4 and the other way round

Originally posted by Elias
What about 3GPP Timed Text? Can *.mp4 store that in full compliance with the MPEG-4 ISO/IEC standard, or is it some kind of a hack/modification like VBR *.mp3 in *.avi? how often do you want to ask this? i think this, your question, has been answered over 10 times already

[Elias]

Thanks bond, this cleared it up for me. I suspected there was something about this when renaming a 3gp file to mp4 and looking in it with mp4UI, there's no profile for the video.

[bond]

Originally posted by Elias
Thanks bond, this cleared it up for me. I suspected there was something about this when renaming a 3gp file to mp4 and looking in it with mp4UI, there's no profile for the video. i think, thats one example where a tool uses the iod (for displaying the profiles), which should be there in .mp4