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Auto-convert: How to set bitrate?


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Posted

Hi - I am using the Live TV "Automatically Convert Recordings to a Streaming Friendly Format" functionality. However, it seems things are being encoded at a very low bitrate (3mbps for 720p, 5mbps for deinterlaced 1080i). Is there a way to modify the bitrate of these auto-transcodes? I would like them to be higher bitrate (say, 10mbps), and transcode down if a client requests something crappier.

mastrmind11
Posted

So then why not disable the feature and let it transcode if the client is unable to play it direct?

Posted

Hi, there are currently no settings, for this, but we are giving ffmpeg a max bitrate of 25mbps with the recording conversion process.

Posted

So then why not disable the feature and let it transcode if the client is unable to play it direct?

 

Good question - I love the responsiveness of clients (e.g. our Fire TV 4k units) when it's playing without the server having to start the transcode process, especially for skipping around. However, it can't play MPEG2 very well natively, so a higher bitrate h264 video would be awesome.

Posted

Hi, there are currently no settings, for this, but we are giving ffmpeg a max bitrate of 25mbps with the recording conversion process.

 

Interesting - I'm not a transcoding expert, would modify the "Transcoding" menu item settings, like decreasing the CRF or changing the preset, cause it to set a higher bitrate then?

Posted

The conversion process currently does not use those settings but perhaps it will in the future. yes that could but it will also do the same for all transcoded playback.

Posted

Is there something I can hardcode / hack to set the target bitrate?

Posted

No but what is the issue with 25mbps? I bet it is probably a higher bitrate than the source feed.

Guest asrequested
Posted

No but what is the issue with 25mbps? I bet it is probably a higher bitrate than the source feed.

 

That is a nice bandwidth.

 

Here's a question. To test, I just recorded a little of two different shows (uncompressed) to look at the bitrates. One show was already broadcast in h.264 and the other was Mpeg2. The bitrates are significantly different.

 

587ac12a0ba2e_Snapshot_440.jpg

 

587ac145264f3_Snapshot_441.jpg

 

Would it be worth adding an option to not compress streams that already are compressed? Maybe analyze the stream and only compress Mpeg2?

Guest asrequested
Posted (edited)

Granted that the smaller of the two is only 720p, but they are also at two different frame rates. Mpeg2 at half the frame rate still has a much larger bitrate. Maybe just remux them to the container that is selected? 

Edited by Doofus
Posted

No but what is the issue with 25mbps? I bet it is probably a higher bitrate than the source feed.

Oh just an arbitrary number. Something higher than 3mbps for 720p / 5mbps for 1080p (I assume it deinterlaces 1080i on transcode, maybe not). 10mbps would be fine tbh.

Guest asrequested
Posted (edited)

Oh just an arbitrary number. Something higher than 3mbps for 720p / 5mbps for 1080p (I assume it deinterlaces 1080i on transcode, maybe not). 10mbps would be fine tbh.

 

What you're asking for is what it actually does.

 

 

587af1ba5733d_Snapshot_444.jpg

 

720p is pretty close 

 

587af2f0095d2_Snapshot_445.jpg

Edited by Doofus
Posted

I suppose the key reason I'm asking would be good context ;) When I enable this functionality, I'm seeing a metric ton of blocking in dark areas of the video. This happens both using software x264, and when Quicksync is enabled (which I sort of expect to produce poor quality).

Guest asrequested
Posted

I suppose the key reason I'm asking would be good context ;) When I enable this functionality, I'm seeing a metric ton of blocking in dark areas of the video. This happens both using software x264, and when Quicksync is enabled (which I sort of expect to produce poor quality).

 

I don't see any blocking. My picture quality is very good. You may need to adjust your settings

 

587af48ea1611_Snapshot_446.jpg

Posted

Heh, read the thread :) What settings are you talking about?

Guest asrequested
Posted (edited)

Heh, read the thread :)

 

Great, thanks!  :blink:

 

 

What settings are you talking about?

 

Your TV, GPU or filter settings for playback. You may have them set too bright and too sharp. 

 

This recording,

 

587bb0f4c22d6_Snapshot_446.jpg

 

587bb10e3c8fd_Snapshot_448.jpg

 

was made with these recording settings

 

587bb1490dd4d_Snapshot_447.jpg

 

My playback experience is very good, indicating that the compression is also very good. 

 

Oh just an arbitrary number. Something higher than 3mbps for 720p / 5mbps for 1080p (I assume it deinterlaces 1080i on transcode, maybe not). 10mbps would be fine tbh.

 

Looking at the bitrate used in my recording, we can see that it is a little lower than 3Mb/s, and playback results in great picture quality, no blocking in the black areas, or anywhere. 

 

I use Theater for windows desktop with madVR for my filter, as it yields better results. 

 

587bb44f94324_Snapshot_449.jpg

 

587bb52d6740f_Untitled.png

 

 

 

587bb4a0d5048_Snapshot_450.jpg

 

 

Can you please provide more information on what your tv source is, what you are using for playback, what filter you are using, what your filter settings are, what GPU you are using and any other pertinent information? I may be able to help you resolve your issue. 

Edited by Doofus
Posted

Doofus, dumb question but how do you access that menu in the lower left of your screenshot with MadVR, play, stop and other functions?

Guest asrequested
Posted

Doofus, dumb question but how do you access that menu in the lower left of your screenshot with MadVR, play, stop and other functions?

 

If you are using madVR as your filter and you window ET, madVR should be in your system tray. Just click on it and it should pop up.

Posted

If you are using madVR as your filter and you window ET, madVR should be in your system tray. Just click on it and it should pop up.

 

Not for me, Windows 10 64-bit.

Guest asrequested
Posted

Not for me, Windows 10 64-bit.

 

What does that mean? I'm using Windows 10 64 bit, too

Posted

What does that mean? I'm using Windows 10 64 bit, too

I don't have madvr icon in the system tray.

Guest asrequested
Posted

Then you must not have MadVR enabled. When playing a video, the icon should be there. How do you have your video settings configured?

Posted

Then you must not have MadVR enabled. When playing a video, the icon should be there. How do you have your video settings configured?

post-44858-0-89107100-1484692720_thumb.jpg

Guest asrequested
Posted

OK, good. So when playing a video and you click on the tray (to expand it) the madvr icon isn't present?

Posted

OK, good. So when playing a video and you click on the tray (to expand it) the madvr icon isn't present?

Correct.  But MadVR clearly is working as shown by the difference in viewing broadcast TV at 1080i, the jaggies are horrible without it.

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