x264enc encoding parameters

[Peter Maersk-Moller]

Hi Ian.

You are recording in interlaced mode. Don't ... unless you display it on an
old interlaced CRT that actually syncs to the same interlace frequency the
material was recorded with .... and very few people does that any more ...
anywhere ... except perhaps north korea

Perhaps the camera being the source for the v4l2src is "interlaced only"
and then you should get another camera.
You need a progressive as opposed to interlaced camera.
Perhaps the camera can do both interlaced and progressive, but not
progressive at the geometry and framerate you have chosen. Try to list the
camera (v4l2 device) capabolities. Use v4l2ctl or something.

Alternatively you can try to add the 'deinterlace' gstreamer module to your
encoding pipeline, but it can only do so much for you. It will never be
perfect.



On Sat, Mar 25, 2017 at 9:24 AM, Ian Davidson <id012c3076 at blueyonder.co.uk>
wrote:

> I have attached a short sample where the effect can be seen.
>
> The feed to the computer is via a video mixer using a composite signal.  I
> expect that that implies that the signal is interleaved.
>
> Where in the pipeline would you recommend that I put the deinterlace?
>
> Thanks.
>
> Ian
>
>
>
> On 23/03/2017 18:48, Tim Müller wrote:
>
>> On Thu, 2017-03-23 at 18:28 +0000, Ian Davidson wrote:
>>
>> Hi David,
>>
>>
>> I have a C program which records a video file from a camera.
>>> The video part of the pipeline (assuming that I have transcribed it
>>> correctly) is
>>> v4l2src ! queue ! videorate ! videoscale ! video/x-
>>> raw,format=(string)I420,width=720,height=576,framerate=(fraction)25/1
>>> ! queue ! videoconvert ! x264enc ! mp4mux ! filesink location=foo/bar
>>> The program works fine and the degree of compression achieved by the
>>> encoder is impressive. However, when there is significant movement in
>>> the image, there is a very obvious 'interleave effect' which remains
>>> visible for quite a while. I would be prepared to pay the cost of
>>> less aggressive compression/greater file size to improve the image
>>> quality.
>>> I have attempted to change the behaviour of the encoder, for example
>>> by setting bitrate to 6000, but I have not found anything which seems
>>> to make any difference.
>>> How should I go about getting better picture quality?
>>>
>> It might be helpful if you put up a couple-of-second-long sample mp4
>> somewhere on your website, so we can check out the exact problem.
>>
>> What is the device that produces this? Is it an analogue video capture
>> device by any chance? Is it possible the device produces interlaced
>> video? You could try adding a 'deinterlace' element to see if it makes
>> a difference.
>>
>> Cheers
>>   -Tim
>>
>>
> --
> --
> Ian Davidson
>
>
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