[mythtv-users] MythTv 0.23 recording resolution and playback issues

Nick Rout nick.rout at gmail.com
Fri May 21 08:11:36 UTC 2010

On Thu, May 20, 2010 at 2:22 AM, Raymond Wagner <raymond at wagnerrp.com> wrote:
> On 5/19/2010 08:18, Ebsen, Mike P. wrote:
> The 10.04 release seems to always record at 1920x1080 resolution independent
> of the broadcaster’s source format.  Old TV shows, like Hogan’s Heros, that
> are still being broadcasted at a very grainy 548x480 are small fields of
> video information with large black unused bands on top, bottom, left and
> right edges of the 1920x1080 *.mpg recorded file.
> Your 2250 is a digital tuner.  The recordings it makes are /exactly/ what is
> being broadcast.  MythTV is not altering the stream in any manner.  If you
> plug in a QAM-capable TV, you will see the exact same thing.
> Another detriment of the 10.04 resolution issue is recorded file sizes.
> Recording the same program on the 9.10 and 10.04 with the same quality
> setting (Normal) results in drastically different file sizes.  The older
> 9.10 release could record an old TV show at a data rate of 780 MByte/half
> hour.  The latest 10.04 release records the same show at a rate of 3.3
> GByte/half hour (and a whole bunch of dark pixels surrounding the relatively
> small image in the middle).
> The quality settings on a digital tuner do absolutely nothing.  MythTV will
> store the stream exactly as it is received, and will do no additional
> processing.
>   I thought one of the attributes of the latest 10.04 release was the newest
> H.264 codecs that were both faster and more efficient at video compression.
> My observations don’t align with these assumptions.
> MythTV does not use H.264 for video compression.  It can only use MJPEG and
> ASP, and then only for analog framegrabbers.  The claim was that a sync of
> the internal ffmpeg library prior to the release of 0.23 brought a better
> optimized H.264 video decompressor, that is roughly 15% faster than before.
> This is irrelevant because everything you ever record off that 2250 will be
> MPEG2.

Why? The broadcaster may transmit h.264, in which case your assumption
is out the window.

Also the HVR 2250 is analogue and digital - so your other assumption is flawed.

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