how to improve video quality?

Question

Hello everyone,

I am using the following code snippets to record screen, and in most situations recorded wmv file is clear enough, but for some part of video it is not very clear (grey color for some parts). What I record is ppt with full screen mode. I am using Windows Media Encoder 9.

Here is my code snippet,

IWMEncSourceGroup SrcGrp;
IWMEncSourceGroupCollection SrcGrpColl;
SrcGrpColl = encoder.SourceGroupCollection;
SrcGrp = (IWMEncSourceGroup)SrcGrpColl.Add("SG_1");

IWMEncVideoSource2 SrcVid;
IWMEncSource SrcAud;
SrcVid = (IWMEncVideoSource2)SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_VIDEO);
SrcAud = SrcGrp.AddSource(WMENC_SOURCE_TYPE.WMENC_AUDIO);

SrcVid.SetInput("ScreenCap://ScreenCapture1", "", "");
SrcAud.SetInput("Device://Default_Audio_Device", "", "");

// Specify a file object in which to save encoded content.
IWMEncFile File = encoder.File;
string CurrentFileName = Guid.NewGuid().ToString();
File.LocalFileName = CurrentFileName;
CurrentFileName = File.LocalFileName;

// Choose a profile from the collection.
IWMEncProfileCollection ProColl = encoder.ProfileCollection;
IWMEncProfile Pro;
for (int i = 0; i < ProColl.Count; i++)
{
    Pro = ProColl.Item(i);

    if (Pro.Name == "Screen Video/Audio High (CBR)")
    {
        SrcGrp.set_Profile(Pro);
        break;
    }
}
encoder.Start();

thanks in advance, George

Answer 1

I would guess that it's a problem with your encoder profile or settings, and not a problem with the code. If you're using the default "Screen Video/Audio High (CBR)" profile in WME9, it's using a video bitrate of 250Kbps, which is pretty low. I'd suggest creating a custom profile in the Windows Media Encoder Profile Editor Utility. Something like this:

awesomesc.prx

Name: Awesome Screen Profile

Audio: WMA 9.2 CBR (32kbps, 44kHz, mono CBR)

Video: WMV 9 Screen Quality VBR (Video size Same as video input, Frame rate 10fps, Key frame interval 3sec, Video quality 90)

Then just change the code to match the custom profile's name.

if (Pro.Name == "Awesome Screen Profile")

The encoder settings would take a much longer post to go through, but if you have not changed them from the defaults, you should be OK.

The Quality-based VBR algorithm can be pretty amazing, and will likely produce a surprisingly low average bitrate, but if VBR won't work for your needs, you can use the Windows Media Encoder Profile Editor utility to import the schia.prx profile that you're using and tweak the settings to find a higher CBR bitrate that produces acceptable quality.