theora - Jul 2009 - Add an intro to a theora file without re-encoding?

Hello,

I would like to add a introduction video (typically a title with fade-in
/ fade-out) at the beginning of an Ogg/Theora video. I generated this
intro video in Ogg/Theora from a sequence of png files.

I would need to do this in an automatic script, because I have many such
videos to process, and without doing any re-encoding step (which would
be very costly because my videos are huge).

I tried to use oggCat:
oggCat final.ogv intro.ogv video.ogv

Unfortunately, this doesn't work well because my intro video has no
sound track to be concatenated with the one in the real video. As a
consequence, the concatenated video only has a video track.

It tried to add a silent track to my introduction video (same bitrate)
with oggzmerge, but oggCat doesn't like the result:
Warning: found unknown stream, this stream will be ignored
Warning: found unknown stream, this stream will be ignored
StreamSerializer::fillStreams: we got a real problem with the stream

Any suggestion for a way to add such an intro video in a simple way?

I am also open to doing it when I encode my main video to Theora... I
would then have:

    * An intro video with no sound
    * An h264 video

Thank you in advance for your suggestions....

Cheers,

Michael.

-- 
Michael Opdenacker, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
+ 33 621 604 642

> Warning: found unknown stream, this stream will be ignored
Might well be skeleton. Try:

oggz rip -c theora -c vorbis -o intro-without-skeleton.ogv intro.ogv

then use that new file. Do this for the other file too, if need be.

2009/7/17 Michael Opdenacker <michael at
free-electrons.com>:
> Hello,
>
> I would like to add a introduction video (typically a title with fade-in
> / fade-out) at the beginning of an Ogg/Theora video. I generated this
> intro video in Ogg/Theora from a sequence of png files.
>
> I would need to do this in an automatic script, because I have many such
> videos to process, and without doing any re-encoding step (which would
> be very costly because my videos are huge).
>
> I tried to use oggCat:
> oggCat final.ogv intro.ogv video.ogv
>
> Unfortunately, this doesn't work well because my intro video has no
> sound track to be concatenated with the one in the real video. As a
> consequence, the concatenated video only has a video track.
>
> It tried to add a silent track to my introduction video (same bitrate)
> with oggzmerge, but oggCat doesn't like the result:
> Warning: found unknown stream, this stream will be ignored
> Warning: found unknown stream, this stream will be ignored
> StreamSerializer::fillStreams: we got a real problem with the stream
>
what was the silent track? What encoder did you use, and was it the
same version as was used for the audio track of the main video?

Conrad.

Hey Michael,
> Hello,
> 
> I would like to add a introduction video (typically a title with fade-in
> / fade-out) at the beginning of an Ogg/Theora video. I generated this
> intro video in Ogg/Theora from a sequence of png files.
> 
> I would need to do this in an automatic script, because I have many such
> videos to process, and without doing any re-encoding step (which would
> be very costly because my videos are huge).
> 
> I tried to use oggCat:
> oggCat final.ogv intro.ogv video.ogv
> 
> Unfortunately, this doesn't work well because my intro video has no
> sound track to be concatenated with the one in the real video. As a
> consequence, the concatenated video only has a video track.
The first file is the main one, oggCat tries to concatenate the others to
fullfill the requirements of this first file. So if there is no audio stream, in
the next files, the audio stream is not used.

If you would do it the other way round, like oggCat final.ogv video.ogv
intro.ogv then oggCat would complain, that there is no audio in the second file
(as the first one has one).
> 
> It tried to add a silent track to my introduction video (same bitrate)
> with oggzmerge, but oggCat doesn't like the result:
> Warning: found unknown stream, this stream will be ignored
> Warning: found unknown stream, this stream will be ignored
> StreamSerializer::fillStreams: we got a real problem with the stream
How do you produce the "silence"? Sounds as if it was not a vorbis
stream!?

The message "We got a real problem ... " is a bit missleading ;-).
This usually means the stream ends invalid (e.g. there is no End-Of-File
indicator or a packet is corrupt because it is read from a livestream etc).
oggCat tries (mostly successfully) to create a valid stream also in such
situations.

However, with version 0.9 I need to rework the error handling :-/
 
> 
> Any suggestion for a way to add such an intro video in a simple way?
I have a small program to create silence (in wave). I then use oggenc with the
same parameters as from the subsequent audio stream and I have had no problems.
I've used that method for my video tutorial.

-Yorn

> Is your silent wav generator available somewhere? That sounds like a
> cleaner way to recommend, for example for people who need to make long
> intros.
I clean that up and send it, when I am at home again this evening.

- Yorn

Hey Michael, all
> Is your silent wav generator available somewhere? That sounds like a
> cleaner way to recommend, for example for people who need to make long
> intros.
I added a new tool called "oggSilence" (I spend my lunch break for
that ;-)

It is not tested completely, but it works for my cases. And it directly produces
an ogg/vorbis file.

Just check out revision 66 from 

https://oggvideotools.svn.sourceforge.net/svnroot/oggvideotools 

- Yorn

PS: Michael sorry for the double post, forgot to reply to all