[vlc] Re: timestamp in video while transcoding from file to file

[GALAD77]

Hello,

thanx for the explanation.
I have one suggestion, but perhaps it is not adequate as I don't know
much about source code.
Just to timestamp appropiately, if transcoding is necessary, one may
change the time each 25 frames with a counter variable.
Would it be simple or does it affect too much code? I will try to look
for the it in the source code, but it seems a big project...

G.

----- Mensaje Original -----
De: "Mark Moriarty" <mfmbusiness at earthlink.net>
Fecha: Jueves, Marzo 10, 2005 1:12 pm
Asunto: [vlc] Re: timestamp in video while transcoding from file to file

> Transcoding is, by definition, required.
> The reason is that timecode insertion is, "under-the-hood", the 
> insertion of
> subpictures that contain a bitmap of the timestamp into the individual
> frames of the source video, blending them in.
> You cannot do that kind of thing in the encoded video, you have to 
> bring the
> video to baseband, the source, raw, frames.  CODECs do some complex 
> math on
> the source video, normally a bunch of fourier transforms, plus 
> things based
> on preceding and following frames, in order to achieve compression -
> - no way
> to add something after-the-fact, against the encoded video.
> As to transcoding timestamp being bad in a file-file transform, 
> good point,
> though I'm not sure how easy to change that would be.  If I want a 
> real-time
> timestamp I run two copies of VLC, one the server doing the timecode
> insertion, the second being a client that restreams the incoming 
> video to a
> new file.  This makes the stream real-time, with a properly stepped
> timestamp.
> 
> -----Original Message-----
> From: vlc-bounce at videolan.org [mailto:vlc-bounce at videolan.org] On 
> Behalf Of
> GALAD77
> Sent: Thursday, March 10, 2005 6:58 AM
> To: vlc at videolan.org
> Subject: [vlc] timestamp in video while transcoding from file to file
> 
> Hello,
> 
> I'm trying to play a streaming input to a file, applying the -time 
> filtertranscode option. The process works fine, but if I transcode 
> from one file
> (f1.ts) to another one (f2.ts) applying the time-filter option, the
> resulting file (f2.ts) does not contain accurately the time label.
> I think this is caused because vlc works 'as fast as it can'. So while
> playing the file, each second the time is update; on the other 
> hand, if
> transcoding from file to file is .say, 3 times quicker, then the 
> visualizedtime label in the f2.ts is changed three times slower.
> Is there a way to correct this issue?
> 
> I think the time filter is very useful, but it can only be applied 
> with a
> transcode option, which is very CPU consuming. Is there a way to 
> play a
> stream/file (that has no time-label) with vlc so that it inserts the
> time-label without transcoding?
> In this case, is it possible to indicate a time starting point, 
> withouttaking it from the system's clock (the source file could be 
> dated a month
> ago)?
> 
> Thanks,
> 
> G.   
> 
> 
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