[Mp4-tech] Timing question
Dave Singer
singer apple.com
Fri Jan 25 09:43:05 EST 2008
At 12:16 -0500 24/01/08, Nicolas El Hani wrote:
>Hello Dave,
>
>I've been referred to you by Gary Sullivan to ask you a question
>regarding MP4 encoding in OS X. I am currently pushing for encoding
>with h.264. I have two questions if you don't mind:
>
>(1) what difference if any is there in using a .mp4 container or a
>.mov container?
There is no difference in question of what *can* be contained, but QT
does expose a difference in the 'export options' for various reasons.
This might be a good question to take to the quicktime mailing list
at Apple, if you want to discuss it further.
>
>(2) Using Quicktime Pro or FCP, I cannot seem to access the "High"
>profile, i.e. I only have the choice between baseline and main. What
>application would recommend for me to encode in the "High" profile?
There are various products that do high profile, and without knowing
a great deal more about your environment and needs, I wouldn't be
able to recommend, and even then, I'd probably be hesitant. Others
on the list may have ideas, of course.
>
>Thank you so much. You can also reply to nicolasonline mac.com if
>you want! Thanks again.
>
>Nicolas
>
>----------------------------------------
>> From: garysull windows.microsoft.com
>> To: nicolas505 hotmail.com; rramani gmail.com; mp4-tech lists.mpegif.org
>> CC: singer apple.com
>> Date: Wed, 23 Jan 2024 21:06:34 -0800
>> Subject: RE: [Mp4-tech] Timing question
>>
>>
>> I'm not sure you would really want to hear my advice about what to
>>do with platform-specific Mac environment issues. :-)
>>
>> Maybe you should get that advice from Dave Singer, who is also on this list.
>>
>> Best Regards,
>>
>> Gary Sullivan
>>
>> +> -----Original Message-----
>> +> From: Nicolas El Hani [mailto:nicolas505 hotmail.com]
>> +> Sent: Wednesday, January 23, 2024 8:47 PM
>> +> To: Gary Sullivan; Ram; mp4-tech lists.mpegif.org
>> +> Subject: RE: [Mp4-tech] Timing question
>> +>
>> +>
>> +> Thank you so much, so basically it is a good idea to with
>> +> anything else than baseline, and you really suggest me to go
>> +> with "high" rather than "main". As I'm a Mac User and do a
>> +> lot of my work on Final Cut and encode in Quicktime Pro, I
>> +> have my two (last) questions hopefully!
>> +>
>> +> 1. Is there a difference between h.264 in a .mp4 container
>> +> or a .mov container?
>> +> 2. Quicktime Pro allows us to export only with the baseline
>> +> or main profile, what program would you recommend for a Mac
>> +> to be able to encode in the "high" profile?
>> +>
>> +> Thank you so so much for all your help!
>> +>
>> +> Nick
>> +>
>> +> ----------------------------------------
>> +>> From: garysull windows.microsoft.com
>> +>> To: nicolas505 hotmail.com; rramani gmail.com;
>> +> mp4-tech lists.mpegif.org
>> +>> Date: Wed, 23 Jan 2024 14:29:14 -0800
>> +>> Subject: RE: [Mp4-tech] Timing question
>> +>> CC:
>> +>>
>> +>>
>> +>> Re: "But if they are all encoded at the same bit rate, the
>> +> quality, the actual perceived quality from all different
>> +> profiles will be the same, it's just that the file size will
>> +> be smaller (main will be smaller than baseline, high smaller
>> +> than main)? But at the same data rate they will be the same
>> +> quality? Thank you so much. I really appreciate it."
>> +>>
>> +>> No. At the same bit rate, High is capable of providing
>> +> better video quality than Main, and Main is capable of
>> +> providing better video quality than Baseline (at least in
>> +> the absence of data corruption/losses).
>> +>>
>> +>> Better compression capability can be used either way --
>> +> either to provide lower bit rate for the same quality or to
>> +> provide better quality at the same bit rate.
>> +>>
>> +>> Best Regards,
>> +>>
>> +>> Gary
>> +>>
>> +>> +> -----Original Message-----
> > +>> +> From: Nicolas El Hani [mailto:nicolas505 hotmail.com]
>> +>> +> Sent: Wednesday, January 23, 2024 2:16 PM
>> +>> +> To: Gary Sullivan; Ram; mp4-tech lists.mpegif.org
>> +>> +> Subject: RE: [Mp4-tech] Timing question
> > +>> +>
>> +>> +>
>> +>> +> Hi Gary,
>> +>> +>
>> +>> +> Thanks so much for your prompt reply, what you said makes
>> +>> +> complete sense, basically what you're saying is that the
>> +>> +> only advantage of using main vs. baseline is that the
>> +>> +> compression from main will be better, and the same with
>> +>> +> "high" where compression of "high" will be better than main.
>> +>> +> But if they are all encoded at the same bit rate, the
>> +>> +> quality, the actual perceived quality from all different
>> +>> +> profiles will be the same, it's just that the file size will
>> +>> +> be smaller (main will be smaller than baseline, high smaller
>> +>> +> than main)? But at the same data rate they will be the same
>> +>> +> quality? Thank you so much. I really appreciate it.
>> +>> +>
>> +>> +> Nicolas
>> +>> +>
>> +>> +> ----------------------------------------
>> +>> +>> From: garysull windows.microsoft.com
>> +>> +>> To: nicolas505 hotmail.com; rramani gmail.com;
>> +>> +> mp4-tech lists.mpegif.org
>> +>> +>> Date: Wed, 23 Jan 2024 12:35:47 -0800
>> +>> +>> Subject: RE: [Mp4-tech] Timing question
>> +>> +>> CC:
>> +>> +>>
>> +>> +>>
>> +>> +>> Nicolas El Hani et al,
>> +>> +>>
>> +>> +>> I would strongly suggest to consider the High profile
>> +>> +> rather than the Main profile. These two profiles have
>> +>> +> basically the same implementation complexity, but the High
>> +>> +> profile has better compression capabilities. The only
>> +>> +> reason that the Main profile exists is that it was the best
>> +>> +> we could come up with at the time (about a year before we
>> +>> +> developed the High profile).
>> +>> +>>
>> +>> +>> The High or Main profile would have substantially better
>> +>> +> compression capability than the Baseline profile. However,
>> +>> +> they would require somewhat more computing resources to
>> +>> +> implement than the Baseline profile, particularly when
>> +>> +> considering implementation in software on general-purpose
>> +>> +> processors. This seems to be the primary reason that some
>> +>> +> implementations (mobile devices, videoconferencing systems,
>> +>> +> etc.) use the Baseline profile. There are also some issues
>> +>> +> relating to loss/error robustness capabilities (with
>> +>> +> Baseline having some advantages over Main/High in that
>> +>> +> regard), but my impression is that those features are
>> +>> +> generally considered less important than the compression
>> +>> +> capability and the computational resource requirements (in
>> +>> +> fact, implementations of the Baseline profile often do not
>> +>> +> actually take advantage of those enhanced loss/error
>> +>> +> robustness features).
>> +>> +>>
>> +>> +>> Best Regards,
>> +>> +>>
>> +>> +>> Gary Sullivan
>> +>> +>>
>> +>> +>> +> -----Original Message-----
>> +>> +>> +> From: Nicolas El Hani [mailto:nicolas505 hotmail.com]
>> +>> +>> +> Sent: Wednesday, January 23, 2024 12:08 PM
>> +>> +>> +> To: Gary Sullivan; Ram; mp4-tech lists.mpegif.org
>> +>> +>> +> Subject: RE: [Mp4-tech] Timing question
>> +>> +>> +>
>> +>> +>> +>
>> +>> +>> +> Hello Everyone,
>> +>> +>> +>
>> +>> +>> +> It's my first time on the mailing list, so excuse me if I'm
>> +>> +>> +> emailing the wrong address or something is wrong in my
>> +>> +>> +> etiquette, just let me know! I'm currently starting a
>> +>> +>> +> business that involves video production. I have a basic
>> +>> +>> +> fundamental question that maybe is not a very smart
>> +>> +>> +> question, but basically is there inherently an advantage to
>> +>> +>> +> encode a video in the "main" profile of h.264 over the
>> +>> +>> +> "baseline" profile. I know the complexity of the main
>> +>> +>> +> encoding is higher. So basically if you had the same file
>> +>> +>> +> encoded in baseline and another one in main, with similar
>> +>> +>> +> data rates (say 1500kbps) would the end result be the same?
>> +>> +>> +> I'm going to be encoding video mostly in VGA resolution and
> > +>> +>> +> start to drift towards 720p. The reason I ask is because
>> +>> +>> +> final delivery to clients would be much better if the file
>> +>> +>> +> could be viewed both on mobile devices (iphone, ipod,
> > +>> +>> +> nokias, etc...) and locally on a computer or TV. But if
>> +>> +>> +> encoding in baseline at the same resolution will compromise
>> +>> +>> +> quality because of its macroblocks or algorithms at the
>> +>> +>> +> encoding stage than it's worth it to use just main and if
>> +>> +>> +> need be for mobile viewing deliver a second file in
>> +>> +>> +> baseline. But it would really be much simpler and would
>> +>> +>> +> streamline the business if baseline could hold up to the
>> +>> +>> +> main. Thank you so much and I hope it's not too much of a
>> +>> +>> +> bother! Cheers.
>> +>> +>> +>
>> +>> +>> +> Nick
>> +>> +>> +> ________________________________
>> +>> +>> +>> From: garysull windows.microsoft.com
>> +>> +>> +>> To: rramani gmail.com; mp4-tech lists.mpegif.org
>> +>> +>> +>> Date: Wed, 23 Jan 2024 11:03:02 -0800
>> +>> +>> +>> Subject: RE: [Mp4-tech] Timing question
>> +>> +>> +>> CC:
>> +>> +>> +>>
>> +>> +>> +>> "Ram" et al,
>> +>> +>> +>>
>> +>> +>> +>> It is not really true that "time resolution" is fixed to
>> +>> +>> +> 30000 in H.263. The standard uses a term called the
>> +>> +>> +> "picture clock frequency". The default PCF is 30000/1001.
>> +>> +>> +> It is also possible to us a "custom PCF". A custom PCF is
>> +>> +>> +> given by 1 800 000 / (clock divisor * clock conversion
>> +>> +>> +> factor), where clock divisor can have values of 1 through
>> +>> +>> +> 127 and clock conversion factor can either be 1000 or 1001.
>> +>> +>> +> There was a very old version of the standard that did not
>> +>> +>> +> support custom PCF, but that capability was added about
>> +>> +> 10 years ago.
>> +>> +>> +>>
>> +>> +>> +>> Also, PAL does not use 29.97 fps. It is 25 fps. NTSC is
>> +>> +>> +> 30000/1001 fps (which is approximately, but not exactly,
>> +>> +>> +> equal to 29.97 fps).
>> +>> +>> +>>
>> +>> +>> +>> Best Regards,
>> +>> +>> +>>
>> +>> +>> +>> Gary Sullivan
>> +>> +>> +>>
>> +>> +>> +>> ________________________________
>> +>> +>> +>> From: mp4-tech-bounces lists.mpegif.org
>> +>> +>> +> [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Ram
>> +>> +>> +>> Sent: Wednesday, January 23, 2024 7:30 AM
>> +>> +>> +>> To: mp4-tech lists.mpegif.org
>> +>> +>> +>> Subject: [Mp4-tech] Timing question
>> +>> +>> +>>
>> +>> +>> +>> Hi Guys,
>> +>> +>> +>>
>> +>> +>> +>> I primarily work with H263 and MPEG4 video codecs. In all
>> +>> +>> +> video codecs thers is this parameters in the stream called
>> +>> +>> +> Time resolution. In H263 they say it's fixed to 30000
>> +>> +>> +>> so that they can achieve 29.97 fps which equals line
>> +>> +>> +> frequencies used in PAL.
>> +>> +>> +>>
>> +>> +>> +>> What is the best value to choose when someone transcodes
>> +>> +>> +> between H263 and MPEG4 in either direction.
>> +>> +>> +>>
>> +>> +>> +>> 'Thanks,
>> +>> +>> +>>
>> +>> +>> +>> Ram
>> +>> +>> +>
>> +>> +>> +>
>> +>> +>
>> +> _________________________________________________________________
>> +>> +>> +>
>> +>> +>> +>
>> +>> +>> +>
>> +>> +>>
>> +>> +>> _______________________________________________
>> +>> +>> NOTE: Please use clear subject lines for your posts.
>> +>> +> Include [audio, [video], [systems], [general] or another
>> +>> +> apppropriate identifier to indicate the type of
>> +> question you have.
>> +>> +>>
>> +>> +>> Note: Conduct on the mailing list is subject to the
>> +>> +> Antitrust guidelines found at
>> +>> +> http://www.mpegif.org/public/documents/vault/mp-out-30042-Ant
>> +>> +> itrust.php
>> +>> +>
>> +>> +>
>> +> _________________________________________________________________
>> +>> +>
>> +>> +>
>> +>> +>
>> +>>
>> +>> _______________________________________________
>> +>> NOTE: Please use clear subject lines for your posts.
>> +> Include [audio, [video], [systems], [general] or another
>> +> apppropriate identifier to indicate the type of question you have.
>> +>>
>> +>> Note: Conduct on the mailing list is subject to the
>> +> Antitrust guidelines found at
> > +> http://www.mpegif.org/public/documents/vault/mp-out-30042-Ant
>> +> itrust.php
>> +>
>> +> _________________________________________________________________
>> +>
>> +>
>> +>
>
>_________________________________________________________________
>
>
>_______________________________________________
>NOTE: Please use clear subject lines for your posts. Include [audio,
>[video], [systems], [general] or another apppropriate identifier to
>indicate the type of question you have.
>
>Note: Conduct on the mailing list is subject to the Antitrust
>guidelines found at
>http://www.mpegif.org/public/documents/vault/mp-out-30042-Antitrust.php
--
David Singer
Apple/QuickTime
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