[mythtv-users] HD-PVR bitrate not being set in v29?

john bolanster at gmail.com
Fri Oct 5 20:11:29 UTC 2018


On 2018-10-04 9:49 a.m., mythtv-users2 at dwilga-linux1.amherst.edu (Dan 
Wilga) wrote:
> I recently noticed that my free disk space was creeping downward, and
> decided to investigate. I discovered that many recordings made since I
> switched from 0.28.2 to 29.1 are consistently larger--sometimes double
> or triple in size.
> 
> Looking further, I noticed that the bitrate of the HD-PVR (not HD-PVR2)
> recordings seems to be much higher than it should be. SoI checked the
> recording profiles in mythtv-setup. I have confirmed that the recordings
> rules in question are using my Low Quality profile, which has this for
> all three (low, med, high) resolutions:
> 
> Avg. Bitrate: 4500 Max. Bitrate: 6200
> 
> What is clear is that recordingsdon't seem to be using this value.
> Taking the output of mediainfo from a 0.28.1 recording and comparing it
> to that of a 29.1 recording of the same program on another night gives
> this diff:
> 
> # diff /tmp/1 /tmp/2
> 5,6c5,6
> < File size : 835 MiB
> < Duration : 33 min 25 s
> ---
>   > File size : 2.52 GiB
>   > Duration : 33 min 24 s
> 8c8
> < Overall bit rate???????????????????????? : 3 490 kb/s
> ---
>   > Overall bit rate???????????????????????? : 10.8 Mb/s
> 21c21
> < Duration : 33 min 25 s
> ---
>   > Duration : 33 min 23 s
> 23c23
> < Bit rate : 2 929 kb/s
> ---
>   > Bit rate : 9 891 kb/s
> 35,36c35,36
> < Bits/(Pixel*Frame) : 0.047
> < Stream size : 700 MiB (84%)
> ---
>   > Bits/(Pixel*Frame) : 0.159
>   > Stream size : 2.31 GiB (91%)
> 48c48
> < Duration : 33 min 26 s
> ---
>   > Duration : 33 min 24 s
> 58c58
> < Stream size : 91.8 MiB (11%)
> ---
>   > Stream size : 91.8 MiB (4%)
> 
> At the same time, while a recording is ongoing, the output of "v4l2-ctl
> -l" gives these values:
> 
> video_encoding (menu)?? : min=0 max=2 default=2 value=2
> video_bitrate_mode (menu)?? : min=0 max=1 default=1 value=0 flags=update
> video_bitrate (int)??? : min=1000000 max=13500000 step=100000
> default=6500000 value=13500000
> video_peak_bitrate (int)??? : min=1100000 max=20200000 step=100000
> default=9000000 value=20200000
> 
> The recording bitrates are maxed. It's as though the values in the
> profile aren't being used, even though they are in the range of
> acceptable values (once you multiply by 1000). Can Anyone else with an
> HD-PVR confirm this?
> 
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20181004/3a7bbf8b/attachment.html>
> 
I'm seeing the same thing on 29. Opened a bug report (13317) with more 
information a little while ago, but don't know if anyone's looking at it 
or whether this also occurs in 30/testing.

It happens to me with my HD-PVR recordings immediately on upgrade from 
.28 to 29-fixes (using Mythbuntu PPA). Bitrate settings from Recording 
Profiles in Mythtv-Setup are applied just fine to recordings in .28, but 
on upgrade to 29 they are ignored, and some sort of what-looks-like 
generic settings are applied to all HD-PVR recordings instead: 720p 
records with VBR at 9000/13500 kbps, regardless of settings in 
Mythtv-Setup being set to 13500 average bitrate and 6500 for max bitrate 
which should, I believe, result in CBR at 13500.

I verified by checking the recordings from .28 and 29fixes both with 
mediainfo, and also by checking in-progress recordings by running the 
v4l2-ctl command to display bitrate info (sorry at work and don't 
remember exact command).

As you would expect, I also see smaller file sizes and a decrease in 
video quality with the lower bitrate recordings on 29, despite the fact 
that the Recording Profile settings for the HD-PVR are unchanged.

I tried swapping in a new hdpvr power supply and a replacement hdpvr 
board to eliminate hardware issues but got the same results. Tried it 
out on a test machine with a fresh install to eliminate corrupted 
database possibility, got same results: bitrate settings work in 28 but 
are no longer applied once I upgrade to 29.



More information about the mythtv-users mailing list