[MPlayer-users] Bitrates and File Size

Ethan John thaen at u.washington.edu
Mon Aug 25 23:57:32 CEST 2003

Oops, add


to that command line. I always do three-pass encoding.

On Monday, Aug 25, 2003, at 13:25 US/Pacific, Joonas Koivunen wrote:

> [Automatic answer: RTFM (read DOCS, FAQ), also read 
> DOCS/bugreports.html]
> On Monday 25 August 2003 22:37, Ethan John wrote:
>> ???
>> How were you aware that I did this? In my original email, there was
>> nothing to indicate that I did this -- I had a unique subject, deleted
>> the quoted text... I'm very confused.
> In mails, when replied, an field like this is added: (this is from 
> your mail
> which to I'm currently answering)
> In-Reply-To: <200308252233.18693.rzei at mbnet.fi>
> Which is used by end-user programs to organize stuff into threads etc. 
> I don't
> know more about this subject though :).
>>> AFAIK this is explained in encoding-tips.txt, check it again.
>> Please, I'm not stupid. I read the doc. It's mentioned briefly at the
>> end, but not to my satisifaction.
> Well I meant this part:
> "From time to time there's a question like 'hey,
> mencoder creates files that are too small! I specified this bitrate and
> the resulting file is 50megs short of the target file size!'. The
> reason is probably that the codec already uses the minimum quantizer
> for nearly all frames so it simply does not need more bits. A quick
> glance at the distribution of the quantizers can be enlightening."
>>>> But in practice, this number is too small -- it yields files in the
>>>> 600-650 MB range.
>>> IMHO  you should target 700MB.
>> I'm not sure you even read what I was saying -- I didn't mention a
>> specific target file size. The formula I think should be correct,
>> should be correct for _any_ target file size given a constant bit 
>> rate.
> If you can't hit the target size, the ratecontrol has decided that this
> quality is enough :) -> "let's not waste anymore bits".
>>> Hint: use 3 pass technique. mencoder will tell you a suggested 
>>> bitrate.
>> MEncoder's bitrate suggestions are LUDICRIOUSLY small compared to the
>> actual bitrates you can get. I used to use these values, but my movies
>> came out to be around 500 MB. Those suggested bitrates are bogus.
> See above. That quote. If you cannot hit target sizes, your video 
> material is
> too easy for the codec. Those numbers have worked for me almost always,
> though I haven't been encoding for few versions..
>> I'll check the file. This may be in the docs, but if it is, it's not
>> easy to find and not well explained. Like I said, i've read the docs
>> inside and out. The video resolution is usually 640x304 or whatever 
>> the
>> aspect of the movie is (I calculate it based on the crop information,
>> automatically). No matter what, it's weird that a movie will have
>> noticeable visual artifacts, still not get up to the bitrate I
>> originally suggested, and the file size will be smaller than the
>> bitrate.
> Could you post your command line? As in all the lavcopts? There might 
> be a bug
> introduced lately, I haven't ever had such expreciences.. (but i've 
> used only
> a bit older versions).
>> Besides, my question wasn't about target file size, it was about why
>> the bitrate of a movie doesn't accurately determine it's file size.
>> Very simple question if you know the answer, I would guess.
> I'd guess too. Maybe I haven't got a clue :). Just that I've never had 
> such
> problems.. It seems that Vladimir Mosgalin has got a clean answer for 
> you :)
> Another reply.. Well I keep posting to this thread if I run into same 
> kind of
> problems..
>> ethan john
> -rzei
> _______________________________________________
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ethan john
Apple Campus Representative
University of Washington

"Books are not circumvention devices. They cannot violate the DMCA. 

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