tap tap - this thing on? 
Some sort of driver bug. Transcoding support on the Pi is WYSIWYG.
Just for grins and giggles, have you tried using the Old Transcoder?
Also try with adaptive streaming off.
i've tried both. Thanks, though.
Any possibility that increasing these values would help?
h264_v4l2m2m_encoder AVOptions:
-num_output_buffers <int> E..V...... Number of buffers in the output context (from 6 to INT_MAX) (default 16)
-num_capture_buffers <int> E..V...... Number of buffers in the capture context (from 4 to INT_MAX) (default 4)
Just wondering if there's not enough memory available for the GPU.
Are you using the Channels DVR image only with nothing else runnning on it?
2GB or 4GB model?
image only, 4GB model. Probably as clean as it can be.
What happened when you streamed that 480p channel?
Don't see errors on that and looks like it streamed for 27 seconds before you stopped it.
Doesn't choke as badly/quickly, but chokes eventually.
Have you already ruled out heating issues? I guess it’s also possible you got a lemon.. 
I've had load pretty high up (probably into 8s but most of that is iowait) and have constantly run on 2 core comskip, without any issues. Fan is constant, too, given the dedicated build.
Not 100% out of the question, but i'd be pretty surprised.
