FFmpeg : Vpre

[Klagar]

Hi !

Here's the continuation of my short series of threads concerning specific parameters in FFmpeg.
So here the question is : is -vpre supposed to work with all and any codec, or just libx264 ?

I tried a two-pass encoding formula. Tested it once with a .mp4 file at the output. Worked fine. Copy-pasted the command line, and only changed the output file extension, -vcodec, -f (and all that stuff) so that the result would be a WMV file instead. I enter the line and, first thing I get, is an error telling me the file preset for slow_firstpass was not found.

Anyone has any clue what I might be doing wrong ?

Thanks as always !

[intracube]

is -vpre supposed to work with all and any codec, or just libx264 ?

vpre is short for 'video preset', and it can be used with codecs other than libx264. However, the preset options needs to be defined in a file in order for ffmpeg to make use of them. My version of ffmpeg comes bundled with a set of libx264 presets, but none for other codecs.

The preset files are stored in different places, depending on what OS you have.

If you search your computer for: libx264-slow_firstpass.ffpreset you can hopefully find the folder with them in.

first thing I get, is an error telling me the file preset for slow_firstpass was not found.

You need to create a separate preset file for the codec you're trying to use.
http://www.ffmpeg.org/ffmpeg-doc.html#SEC13

This is relevant for Windows users wanting to know where to store their preset files:
http://forum.doom9.org/showthread.php?t=148777

[bat999]

..

[Klagar]

Now I understand.
Thanks Intracube, your reply gave me the idea to actually open one of my .ffpreset files and see what it contained. I thought it would be just gibberish, comparable to .dll files or so, but now I see what purpose they really serve.
That's gonna help me a lot.
In the end, I can just copy my libx264 presets, rename them, and they should pretty much work with other vcodecs, right ?
Gonna try it out !

Thanks again !

[intracube]

In the end, I can just copy my libx264 presets, rename them, and they should pretty much work with other vcodecs, right ?

Not all parameters are interchangeable or relevant for different codecs. You need to find the details for the codec you want to use.

EDIT: What are you using for -vcodec, msmpeg4?

[Klagar]

I use wmv2, libx264, some libxvid and I think I have like one line that uses libtheora.
I've begun my investigation, I see what you mean, I started with libx264 and switched to wmv2 and FFmpeg told me the following error : [wmv2 @ 01e88010] b frames not supported by codec
I just deleted the -bf parameter from the preset and it seems to work fine so far. I guess I'll go by trial and error to adapt to the other codecs.
Fortunately, the only two presets I pretty much use are slow and slow_firstpass, at least for now. So it shouldn't prove too fastidious.

[intracube]

I see what you mean, I started with libx264 and switched to wmv2 and FFmpeg told me the following error : [wmv2 @ 01e88010] b frames not supported by codec
I just deleted the -bf parameter from the preset and it seems to work fine so far. I guess I'll go by trial and error to adapt to the other codecs.

One thing to watch out for; even if ffmpeg converts your videos without error, and the file plays back on your computer - the video might not play on standalone DVD players that would otherwise play wmv/DivX videos, as they often have additional restrictions with the formats they support.

This might not be directly related to what you're trying to do, but this page shows some some of the limitations of the iPod and PSP that need to be taken into account:
http://rob.opendot.cl/index.php/2007/01/11/ipodpspx264-encoding-guides/

[Klagar]

Nice !
As you said, this is not directly related to what I'm trying to do, but nobody said it wouldn't ever be. I shall keep that info preciously