[MPlayer-dev-eng] 3 pass encoding syntax poll

[Danny]

Loren Merritt ha scritto:

> On Sat, 5 Feb 2005, Loren Merritt wrote:
>
>> When I came up with the current syntax for N-pass encoding with lavc 
>> or x264 (pass=1 on the first pass, pass=3 on all subsequent), I 
>> though it was the most logic method: N-pass simply enables both 1st 
>> pass stats file and 2nd pass ratecontrol, so I used 3 == 1|2.
>> However, I have seen many confused users, so apparently this isn't so 
>> intuitive, and nobody reads the section in the manpage describing its 
>> usage.
>> So I have decided to change the syntax and/or behavior of multipass 
>> encoding. But since I was wrong the first time, I will now ask 
>> opinions before choosing a replacement.
>>
>> * Always perform N-pass encoding. (It is, after all, identical to 2-pass
>>  if you run only one Nth pass.)
>>
>> Additionally (especially in the last option), I think it would be 
>> beneficial to use separate statsfiles for each pass, so that 
>> cancelling an encode doesn't erase the results of previous passes. 
>> This would require changing the -passlogfile option somehow, since 
>> there would be multiple files to specify. How best to go about this?
>
>
> OK, unless there are arguments to the contrary, I will now implement:
> Always use N-pass encoding instead of 2-pass.
> The statsfilenames will be derived from the value of -passlogfile as:
> If the filename contains "%i", replace it with the pass number, else 
> append the pass number.
>
> This allows 2-pass encoding with no changes from the current syntax, 
> and allows N-pass encoding by simply incrementing vpass.
>
>

    What about use a temporary file to store the current log and copy it 
on the real logfile only at the end of the encoding ?

    In this way if you stop an encode session you have the (complete) 
previous log and you can start another encode, maybe with differents 
parameters.

    This let you usa as many passes as you want without use a lot of log 
file.

     Maybe another solution is to keep the log file in memory (if you 
have already a log file you know how many frames you encode). 

    Daniele Forghieri



> P.S. If the filename stuff is common to ve_lavc and ve_x264, where 
> should it go?
>
> --Loren Merritt
>
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