[mythtv] [PATCH] -- picking wrong AC-3 audio stream to play

[Brad Templeton]

On Thu, Feb 17, 2005 at 01:11:35PM -0500, Doug Larrick wrote:
> Brad Templeton wrote:
> > Again, am I missing something?  When does the player play DVDs?  Or is
> > this something planned for the future, switching from mplayer for that
> > function?
> 
> 1. I think you can specify to use the internal player for MythVideo.  I
> don't use MythVideo at all, so I don't know.
> 2. I believe the key phrase used before was "perfect dvd rip"; you'd
> have to do an archive search to find that discussion.

Thanks.   In looking more at the code, I note that what it does is
immediately grab the first (meaning last because it is counting down)
AC-3 codec stream it finds.   Only if it finds no such stream does it
try to pick the stream from another codec with the most channels.

My patch changed this so it picks the "first" (as in lowest numbered)
AC-3 stream instead of the last.

What is confusing it is that the PBS shows have 3 streams, all with
an AC-3 codec.   I am not sure what's in the other streams, I just
know that the first one (0.1) is the real one, and the last one 0.3 (that myth
picks) is silent.  I don't know what's on 0.2.  Presumably
their long term intention is SAP style stuff.

    Input #0, mpegts, from 'myth://192.168.123.10:6543/2010_20050216110000_20050216120000.nuv':
    Stream #0.0[0x41]: Video: mpeg2video, 704x480, 29.97 fps, 3975 kb/s
    Stream #0.1[0x44]: Audio: ac3, 48000 Hz, stereo, 384 kb/s
    Stream #0.2[0x45]: Audio: ac3, 48000 Hz, stereo, 192 kb/s
    Stream #0.3[0x46]: Audio: ac3, 48000 Hz, stereo, 192 kb/s


In this case, the only way to pick is by order, or by attributes.  Bitrate
would work here but I don't know if that's universal.

Unfortunately the true long term solution adds yet more UI, in that myth's
player, like a DVD player, might need to have a menu to let a user select
the audio stream if multilingual streams are arriving.

---- side note on video

This recording came from PBS-Encore.  It is Nova, this one is in
widescreen but not HD.   The recording at 1080i is overkill and 6 gigs per
hour.  The recording at 480i above is much smaller at 1.6gb, but is much
blurrier.   This is in part because it's letterboxed in a 4:3 window, which
seems really dumb but it seems as though it's even more than that.  The
1080i recording is effectively EDTV, 720x480p, but upsampled to 1080i.

An annoying choice here -- for best quality, a 6.3 gb file, or accept less
quality at 1.6gb.  Probably down the road the right thing to do is
to transcode down to 960x540p or something and get a small file but
remain progressive and keep all the resolution.  (the deinterlace is
trivial if you go to 540p)