Gstreamer doubts

[Stirling Westrup]

On Mon, Aug 11, 2014 at 8:27 AM, 007GK <sneha.nie at gmail.com> wrote:

> I was trying gstreamer with various plugin/elements and could not
> understand few basic terms.
>
> 1. When to use sync=false, sync=true, sync=1 with sink elements?
>

sync=true, sync=1 are the same. sync=false, sync=0 are also the same. Use
whichever is more convenient.

Normally you use sync=true when you will have someone watching the results
in real-time, as it synchronizes the output to the speed the video and
audio should be played at.

If your pipeline just does processing, (ie, reads from one file and writes
to another) then you can set sync=false and the pipeline will run as fast
as it can.


>  2. When to use autovideosink?
>

When you don't want fine control over which monitor you are sending output
to, or in a single-monitor setup, autovideosink saves effort by finding a
video output (usually a monitor) and sending the video there.


> 3. Which is the demuxer to be used with decklinksrc?
>

Decklinksrc doesn't need a demuxer as it produces separate audiosrc and
videosrc outputs. You only need a demuxer when you are trying to convert a
single mux'ed stream into a number of video and/or audio streams.

I should point out that there is a known bug with decklinksrc that it
doesn't work with its output set to sync=true, so you need to use
sync=false. The bug is being worked on, last I heard.


> 4. What is ffmpegcolorspace element?
>

It uses the ffmpeg library to convert from one video colorspace (such as
RGB) to another (such as YUV). It can, in general, convert between most
compatible forms of video encoding.

However, its also a 0.10 element. I *strongly* recommend moving to 1.0 and
later, as the early versions are very buggy and are not being maintained
any more.

5. For below pipeline gst-launch errors out saying : WARNING: erroneous
> pipeline: could not link queue0 to audioconvert0
>

I have no idea why just swapping the order of specifying video and audio
components should cause gst-launch to fail. Sorry.

-- 
Stirling Westrup
Programmer, Entrepreneur.
https://www.linkedin.com/e/fpf/77228
http://www.linkedin.com/in/swestrup
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