HD PVR 2 review / feedback

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mythrec
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HD PVR 2 review / feedback

Post by mythrec » Thu Dec 28, 2017 8:23 am

I know there is some occasional interest in the HD PVR 2. I've therefore written up some details about it so people can see what they might be in store for https://plasticwrap3d.wordpress.com/hau ... ux-mythtv/

I'm afraid it's a bit technical / wordy and I don't have the time to generate any sample images etc. I'm sure people will get the gist regardless.

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paulh
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Re: HD PVR 2 review / feedback

Post by paulh » Thu Dec 28, 2017 7:10 pm

Yeah I got a HD PVR2 sometime ago hoping Hauppauge would eventually produce a proper driver for it. I did try the test app and even tried to fix it but gave up and it's now consigned to the spare parts bin as an expensive mistake :(

I managed to get hold of a Magewell USB 3.0 HDMI capture device. It's very expensive and doesn't even have an encoder, you just get the raw audio and video frames from it, but so far it appears to work OK. It appears in Linux as a V4l2 video and audio device that you can read the raw data from. At Full HD resolution the amount of data produced is quite large but you can change the output resolution to suit what you need.

One advantage of this device over the other encoders is there is zero delay in the video output, Magewell say it's less than one frame, so if you hook it up to an STB you can see any interaction with menus, epg, channel changes etc right away. With the other encoders you get about a 2 second delay which makes it painful to use.

Gribnif
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Re: HD PVR 2 review / feedback

Post by Gribnif » Thu Dec 28, 2017 7:58 pm

I recently broke down and bought a Blackmagic DeckLink Mini recorder. Like the Magewell mentioned previously, it is strictly a capture device. One difference is that it uses a PCIe slot. It is also fairly low-cost (about US $137). It is capable of capturing 1080i30 along with up to 16 channels of audio via HDMI.

Saving full 1080i30 video to disk is very space-intensive, to the tune of nearly 1Tb/hour. However, I have had pretty good luck so far using a custom-compiled version of ffmpeg to read data directly from the /dev/blackmagic device created by the card's Linux kernel driver with ffmpeg's "decklink" input device. Even on my fairly old AMD A8-7600 I can have ffmpeg read the data, encode it using H.264/AC-3, and send it to MythTV in a TS stream without taxing the CPU or sacrificing quality very much.

Of course, due to the encoding, there is some latency. I haven't yet measured it, but my sense is that it is still less than what it is with the HD-PVR.

In order to send the data to MythTV, I've had to modify the mythfilerecorder utility that comes with Myth. I plan to release this as a fork or perhaps a patch once I get some kinks worked out.

schaff
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Re: HD PVR 2 review / feedback

Post by schaff » Sun Jan 21, 2018 1:50 am

Gribnif wrote:
Thu Dec 28, 2017 7:58 pm
In order to send the data to MythTV, I've had to modify the mythfilerecorder utility that comes with Myth. I plan to release this as a fork or perhaps a patch once I get some kinks worked out.
Hi Gribnif. I'm curious how you managed to get your device working. I recently acquired a Magewell Pro Capture PCIe card which has V4L2 support via a Linux driver (I'm on Fedora 27, Myth 29). While the card works well with ffmpeg to capture and mux the alsa audio stream into mp4, I can't figure out how to configure MythTV to recognize this card -- and it may never work natively. A helpful IRC chat pointed me to consider hacking on "Import test recorder" capture device in mythtv-setup, but it sounds like you have an approach that may work for this card as well. Would you be willing to share a bit more about your custom ffmpeg and the mythfilerecorder code you've modified as well?

Thanks!

Gribnif
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Re: HD PVR 2 review / feedback

Post by Gribnif » Mon Jan 22, 2018 2:44 pm

schaff wrote:
Sun Jan 21, 2018 1:50 am
Hi Gribnif. I'm curious how you managed to get your device working.
My code, such as it is, is pretty rough right now. I definitely intend to share what I've done with the world, but I'm still having a big problem that I haven't had time to figure out. I can record one program (or live TV channel) just fine, but if there is second program scheduled to record back-to-back, or if I tune a new channel in Live TV, things get confused and recording stops.

If you'd like to pm me your email address I can send you the source for the modified version of mythfilerecorder I've been working on. Since you have ffmpeg working with your card already, you should be able to use this to capture into Myth--with the limitations listed above.

schaff
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Re: HD PVR 2 review / feedback

Post by schaff » Wed Jan 24, 2018 2:09 am

Thanks. I'll PM you but apparently my post count is still too low...maybe this post will help and I can try.

I made a bit of progress myself using Import recorder approach starting from the sample script here: www<dot>mythtv<dot>org/wiki/Import_recorder, but have hit some issues myself. The scheduler sometimes doesn't seem to be behaving properly as many of my scheduled recording didn't happen and I see the same issue as you with back-to-back recordings. In addition, the actual recordings are quite choppy and the audio requires an ffmpeg flag (-itsoffset) to sync with the video. I'm not sure if this is the ffmpeg settings I'm using or this machine is just too old to keep up.

I'll be trying some other hardware this weekend. Maybe we can exchange some ideas.

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