[mythtv-users] Android Mythfrontend on Chromebook

Ken Mandelberg km at mathcs.emory.edu
Thu May 19 23:15:11 UTC 2022

Stephen Worthington wrote on 5/18/22 01:48:
> On Tue, 17 May 2022 21:57:24 +0000, you wrote:
>> On Tue, May 17, 2022 at 9:49 PM Ken Mandelberg <km at mathcs.emory.edu> wrote:
>>> All my recordings are from Xfinity, and it turns out almost all of those
>>> in recent years are in 720. If I go quite a few years back into my
>>> recordings, Xfinity had them in 1080 and those do run ok. Now that I
>>> look harder there are in fact some newly recorded ones from a nostalgia
>>> channel that are in 1080 and they do play.
>> Check the encoding.  (Pretty much) all the newer
>> 720p's are going to be MPEG4, and at least some
>> of the older recordings are likely MPEG2.
>> Some hardware (or the OS) may report it supports
>> codecs that they do not actually properly support
>> (so the result is either hangs/black screens, or
>> bad visual artifacts).  Chromebooks all over the
>> place in terms of proper support (even when
>> the hardware supports the codes, the OS version
>> may not).  Some vendors have a list of known
>> devices that they override the selection for
>> (and fall back to software decode, which itself
>> may not work if the processor is not sufficiently
>> capable).
> TV programmes that are 1080 are usually 1080i, and deinterlacing is
> always a problem on any except the best GPUs.  If it has to be done on
> the CPU, you will likely need to select a lower mode that the CPU can
> cope with.
I looked at two very recent recordings both from the local PBS 
affiliate. One was from their main channel, the other from their 
secondary channel. Both delivered by Xfinity/HdHomerun. The secondary 
plays in the Android Mythfrontend, the main channel doesn't. From the 
mediainfo below the issue seems to be AVC vs MPEG-2. I presume AVC is 
essentially MPEG-4.

One thing I can do is run the old mythplayer app which will fetch the 
myth data and run an external player like mxplayer which handles the AVC 
video. I guess the codec support through the Android API is just not up 
to the task of AVC.

The mythfrontend marks the main channel recording as 720. More 
specifically the mediainfo program shows

ID                                       : 1021 (0x3FD)
Menu ID                                  : 1 (0x1)
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High at L3.2
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 4 frames
Codec ID                                 : 27
Duration                                 : 43 min 52 s
Bit rate mode                            : Constant
Bit rate                                 : 3 454 kb/s
Nominal bit rate                         : 5 000 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels

The secondary channel recording shows

ID                                       : 1006 (0x3EE)
Menu ID                                  : 1 (0x1)
Format                                   : MPEG Video
Format version                           : Version 2
Format profile                           : Main at Main
Format settings                          : CustomMatrix / BVOP
Format settings, BVOP                    : Yes
Format settings, Matrix                  : Custom
Format settings, GOP                     : Variable
Format settings, picture structure       : Frame
Codec ID                                 : 2
Duration                                 : 29 min 57 s
Bit rate mode                            : Variable
Bit rate                                 : 1 797 kb/s
Maximum bit rate                         : 18.0 Mb/s
Width                                    : 528 pixels
Height                                   : 480 pixels

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