[mythtv-users] Recording from input video on demand, no tuner; update: troubles capturing video using RPI4

[Peter Bennett]

On 2/28/23 20:52, Stephen Worthington wrote:
> On Tue, 28 Feb 2023 14:39:03 -0500, you wrote:
>
>>
>>>> I don't know if it will help you, but as of Mythtv v33, the mythexternrecorder application now lets you set "per channel" tuning command. See:
>>>> https://www.mythtv.org/wiki/Example_Configuration_files#Mythtv_v33_Example
>>>>
>>>> That means your tuning command could be a no-op for specific channels that you have defined.
>>>>
>>>> John
>>>
>> So I have been ‘experimenting’ with this and I think I have set up something incorrect for incoming video.
>>
>> The hdmi device is usb, one of those that are 10-20 bucks, and from what I can tell it is creating a v4l2 mjpeg video stream with a PCM audio stream on  USB audio.
>>
>> Using ffmpeg, I can create an avi with it, and also an mkv with it , and have tried multiple ways to create an output stream for mythtv to use.
>>
>> I am trying to keep processing down to a minimal amount since I am trying to use a Raspberry Pi 4b with 4GB ram running mythbackend to capture the video stream.
>>
>> If I try to use any mpeg2 or mp4 transcoding, I get in trouble with using too much cpu. Any ideas as to what I can try to capture with little or no transcoding effort on the RPI 4b? Or am I asking too much from the RPI4 to capture it.
>>
>> Regards!
> I know nothing about those cheap devices, but the first thing I would
> try would be to just store the data directly to a .ts file, as
> mythbackend does for DVB streams.  If mythfrontend can play the
> result, then all is well.  If not, then you can set up an automatic
> non-real time transcoding job to be run at low priority after the
> recording finishes (or the job can be run in parallel with the
> recording).

FWIW I have been using those USB devices for about 2 years as my main 
MythTV capture devices. The scripts and info are here:

https://github.com/bennettpeter/MythTV-LeanCapture#readme

My scripts encode to H264. The RPI is far too slow to encode the stream 
(as noted in the readme). You may be able to change the ffmpeg 
parameters to output an MJPEG TS without any encoding.

Peter