[mythtv-users] Post-Recording: Transcoding, Commflag, Auto-Expire Settings

[Dewey Smolka]

On 10/27/06, Taylan Pince <taylan at taylanpince.com> wrote:
>
> Hello,
>
> I have been using my MythTV system for about two months now, and I am
> really happy with it. But I have some issues about the post-recording
> processes that I still cannot figure out. Any help is greatly
> appreciated.
>
> - My recordings are taking more space than I would like: 1 hour is
> about 2.2GB, even though I check auto-transcode when I am scheduling
> through mythweb. How can I make sure they are further compressed?
> Also, how can I re-encode my older recordings to reduce their size?

I'm guessing from the filesize that you're using an MPEG-2 encoding
card. For auto-transcode, you need to first adjust your recording
profile (Utilities/Setup -> Setup -> TV Settings -> Recording Profiles
-> Encoder Card) to enable the Autotranscode option.

Next, you need to configure the transcoder profile (Utilties/Setup ->
Setup -> TV Settings -> Recording Profiles -> Transcoders). As an
example, I use the Autodetect from MPEG-2 transcoder, set MPEG-4 for
compression with these settings: Bitrate: 2200, max quality: 2, min
quality: 15, max quality difference: 3.

These settings will reduce a one-hour recording from around 2.2 GB to
around 750 MB.

You can compress recordings even further using nuvexport, which will
compress, rename, and cut commercials out of a recording (provided you
have a cutlist defined).

> - Most of my recordings are showing "has commflag: No" on the mythweb
> interface. How can I make sure the commercials are flagged? I read
> that it is possible to cut those out to reduce the file size even
> more, how can I automate this?
>

Com flagging is set globally in Utilties/Setup -> Setup -> TV Settings
-> General or can set/unset for individual recordings or recording
rules.

The com flagging doesn't actually remove the content but inserts flags
into the stream to indicate where Myth thinks the breaks are. I find
it works about 90-95 percent of the time.

The cut list generated by comflagging survives the transcode. If
you're planning to use nuvexport to remove commercials completely, you
shoud start a playback of the recording, hit 'e' to edit and 'z' to
load the cutlist. Make sure the cut points are where you want them.
Unfortunately it's just not accurate enough for me to do this
automatically without double-checking the cut points.

>
> - All my recordings show "auto-expire: Yes" on mythweb. Why would a
> recording expire when I scheduled it to be recorded (I obviously want
> to keep it)? How can this be changed, and how can I make sure it
> never happens again?

Autoexpire means that when the disc is full, Myth will automatically
start removing the oldest and/or lowest priority recordings to make
room for new recordings. If you're not short of space then nothing
gets expired.

>
> - Finally, how can I change these settings using the command line
> rather than the myth interface? Are there any tutorials that can
> point me in the right direction?

I'm not aware of any way other than the frontend UI to adjust these
settings. You do, however, run mythtranscode and nuvexport from the
CLI.