[MEncoder-users] Mencoder params

[Raimund Berger]

RC <cooleyr at gmail.com> writes:

> On Wed, 21 May 2008 17:45:29 +0200
> "Raimund Berger" <raimund.berger at gmail.com> wrote:
>
>> (1) You don't need to encode audio on the first pass. To save cpu
>>     cycles, rather use -oac copy
>
> Quite the contrary.  Changing the audio encoder will very likely cause
> different frames to be dropped, resulting in lower quality 2-pass
> encoding, and potentially the second-pass crashing as well.

I don't see that. Frame dropping/duplication will happen only to
sustain the output frame rate, to which audio is synced at it's
respective pcm sample rate, independent of any audio target encoding
format. Especially, the audio encoding should not matter whatsoever
regarding video frame handling. If you know more about algorithms at
work deviating from this common scheme, please elaborate in detail.

Apart from that, I've used those proceedings on many encodings,
straight PAL or NTSC IVTC'd, and nothing ever crashed. Also, from my
logfiles, I can't corroborate the statement that frame
skipping/duplication differs on passes when a simple audio copy is
done on the first pass.

>
>> (4) "raw" in faacopts prevents remuxing and doesn't have any obvious
>>     advantage; I wonder how you came up with this
>
> Necessary for direct output to mp4 with mencoder/lavf, as explained in
> the man page. No wonder you think that muxing to mov/mp4 is broken...


Didn't find anything of what you say in the lavf section. In the faac
section it rather says on "raw": "Do not set this flag if not
explicitly required or you will not be able to remux the audio stream
later on."

Again, it'd be helpful if you pointed to the exact section where this
requirement is supposedly made explicit.