Extract mean mapped base phred quality by mapped location from BAM file

[ugm6hr]

I would like to display a histogram of mean mapped base phred quality (call quality, not mapping quality), with chromosomal location on the "x-axis"
I have recalibrated & realigned BAM files from Illumina sequencing for a small target.
Is it possible to extract this data presented by chromosome location?

Obviously, IGV will display individual reads, with individual base quality. Can the mean quality be automatically extracted?

Essentially, I would like to compare this with depth of coverage by chromosomal location, which coverageBed extracts from the BAM file directly.

Thanks.

[adaptivegenome]

You could write a script that grabs the quality values from a BAM file and averages them over a sliding window.

[ugm6hr]

Thanks adaptivegenome.
That is beyond my programming skills. I was hoping that someone may have done something similar already...
I may make do with the BamUtil: stats Q20% as an alternative way of representing this data.
The purpose is to try and identify the cause of incorrect variant calls... Is base-specific read quality a factor?