SGTV7 MKV converter

[ehfortin]

Hi,

I'm using SageTV 7.0.15 and tried to play with MKV for a few days. I'm quite happy with MKV HD standard for most recorded show. Now, I have the problem that my fast computer is not the one running SageTV. The server used for SageTV is just too underpowered to do a conversion while doing recording or playback so... is there a way to use either my SageTV client (more processing power) or a completely unrelated desktop (can be Windows or Linux) to create the exact same MKV files as SageTV 7.0.15 would generate from a HD-PVR .TS file? If I remeber well, it has to support HD (16:9) with 30 fps and dolby digital over 48Khz stereo.

Can this be done? And is there a way to have those converted file part of SageTV like the one created by SGTV?

Thank you.

ehfortin

[wayner]

I think the MeidaShrink addin may be able to do this, you could kick off MediaShrink jobs from SJQ which can run on any PC on your LAN. But what is the advantage of an MKV vs the original .TS file that comes from your HD-PVR? I believe they both use the H.264 codecs and the main differnce between the two is really the container rather than the video files itself.

[Fuzzy]

I agree, there's really no need to recompress the HD-PVR streams.. all you'll end up doing is dropping quality. If space is a concern, you'd be better off lowering the HD-PVR's original compression settings.

Oh.. and SGTV?

[ehfortin]

Hi,

I'll look into that soon.

SGTV = SageTV, sorry for this. That's the acronym I'm using for SageTV.

Thanks.


ehfortin

[ehfortin]

Well, I played with mediashrink. It certainly create mkv that are a lot smaller then the original TS.

At first, I thought it could make sense to just reduce the size of the .TS by changing the setup for the recording. However, I'm not that sure anymore. I have the feeling that reducing the size of the TS by configuring SageTV/HD-PVR to do lower quality would not do the same. I'm thinking it may result in a lower quality recording where a conversion to MKV can still be relatively high quality but be smaller.

My reflexion is that the HD-PVR never has more processor power so... "reducing the quality" would not be because of a greater compression but because of letting go more information.

Does it make sense? If so, then mediashrink is the only option for me as my sagetv CPU is an Atom so... too underpower for a conversion. My desktop is better for this.

Now, I have to do some research because the documentation on mediashrink seems to indicate I can remove the .ts and put the .mkv and SageTV will, after some time, recognize this and will use the .mkv when playing the specific show but... doesn't work here. I have to copy the file in one that is managed as a video path (imported video). Which means the file will be showing as a Video but not under TV anymore.

Any idea?

Thanks.

ehfortin

[Fuzzy]

There is nothing about an MKV file that makes it any smaller than a .ts file. They are both just containers, and if you are comparing the H.264 TS file from the HD-PVR to a H.264 MKV file, at the same quality, they will be approximately the same size. The only way to make h.264 smaller than what the HD-PVR puts out i to reduce the quality of the video. H.264 is pretty much the top of the line compression at this point. You will definitely get better results with recording directly to, say 8Mbps, than you will recording to 12Mbps, then transcoding to 8Mbps, as the transcoding will add in more compression artifacts.

[ehfortin]

Hi,

It make sense as well. I was just not sure if it was the case as the CPU in a computer is typically a lot faster then what I expect to be in the HD-PVR and it take more time to convert then the actual playback time so... I was assuming there was some optimization that a "live" encoder could not be able to provide.

Do you know what are the bitrate for each settings available in SageTV7? It goes from "Fair" at 1.8 GB/hr to Best at 5.9 GB/hr.

Compared to numeric TV, which setup is about equivalent (make no sense to record at a higher level then what is received from the cable company imho)?

Does changing from higher quality to lower quality change anything related to audio or it is always the same audio quality?

Thanks a lot.

ehfortin

[Rico66]

Note that you can specify the target bitrate directly by defining a custom recording quality setting (see e.g. http://forums.freytechnologies.com/f...d.php?p=286840) and use that instead of one of the predefined ones. Specifically using vbr instead of cbr is a good idea if size matters.

Audio is not affected at all by these settings.

[ehfortin]

Hi,

I've done some testing since yesterday. I've setup the HD-PVR *and* default recording to "Fair" but... I'm getting the same 3.8 GB/hour that when it was configured to "Great". I've done my changes in "Multimedia/Recording Quality". Is there anything else to do? As I changed both place to the same "Fair", I was expecting any recording after that to use this new setup. Particularly as I forced some new manual recording from the guide.

Thank you.

ehfortin

[jeeves5454]

ehfortin,

For HD-PVR, the system does not change the recording quality. The recording quality is a digital reproduction of the signal/output from the box. Changing the default quality will not make a difference to the end result.

[Opus4]

Originally Posted by jeeves5454

For HD-PVR, the system does not change the recording quality. The recording quality is a digital reproduction of the signal/output from the box. Changing the default quality will not make a difference to the end result.

That is incorrect. SageTV does set the recording rate for the HD-PVR. The HD-PVR is not a digital tuner that simply saves the bitstream as it comes in, such as for QAM or ATSC; instead, it takes an analog input (component video) and digitizes that input.

When setting the overall default recording rate, you can choose a rate that isn't compatible with the HD-PVR & a different one will be used. But, you can set the default recording quality for the HD-PVR tuner, at which point only the HD-PVR compatible recording quality options will be shown.

- Andy