Transcode HDTV myth recordings

MythTV hasn't save recordings as .nuv files for some time. They are now .mpg files

You can transcode recorded .mpg files from within Mythtv, using mythtranscode. I haven't this done for a while, but I found a How-To that looks to be correct
.
http://www.myhdbox.com/mythtips/2006...s-for-hdtv.php

The resulting file is a .nuv file. This will play on VLC in Windows. When I need a divx file, I transcode on a windows PC with the free DrDivX application.

I'd like to revisit this topic. I am also interested in trancoding HDTV captures after commercial flagging has been performed. I want to convert the files to a DVD mpeg file for burning to share with friends.

TIA

Mytharchive plugin --> http://www.mythtv.org/wiki/index.php/MythArchive

This does work but does not pickup the commercial flagging.

Hmmm...
http://www.mythtv.org/wiki/index.php...of_MythArchive
I haven't really tried this...maybe someone else can help.

I use VirtualDub on the raw mpg and just mark the commercials myself (I find that the commflagging is not 100% enough to let it autoskip those parts).

OK, I tried this, and I have successfully removed the commercials too.

First, you want to make sure that the commercial breaks are properly marked. Play the recording in MythTV, as you normally would. When the recording starts, press the E key, to bring up the edit mode. Here you can review the commercial breaks, and even add new ones. When done, press the E key again to exit.

More detailed info on this can be found here:
http://www.mythtv.org/wiki/index.php/Creating_a_cutlist

Now that the commercials have been properly marked, you can create a cut list. This is done using the terminal command, mythcommflag and the --gencutlist option.There are two methods, one uses the channel ID and start time, whatever those are. The other is to specify the path/name of the file. I used the path/file name method. My recordings are in the /video/TV folder, so my command for last Mondays "How I Met Your Mother" episode, looked like this.
More detailed info on mythcommflag can be found here:
http://www.mythtv.org/wiki/index.php/Mythcommflag

Now start this:
Optical Disks-->Archive Files-->Export Video Files-->Create DVD

Select the options that you want. I selected "Make ISO Image".When I selected "Burn to DVD", it failed. Although the files were there, and I manually burned them to a DVD. (I was using a DVD+RW, and now I see that I had the wrong media selected) On the next page, choose "Add Recording" to select the recordings to use. When you choose a recording that has a cut list, the option to use it will then be available. Make sure that you then select that option.

Go through the rest of the pages and make the DVD as you want it.

Before doing any of this, you should set up Mytharchive. You need to have a folder with space for the DVD. Set that and the video format (NTSC) here:

Utilities/Setup-->Setup-->Media Settings-->Archive Files Settings

waterhead,
Thanks for the info. I will give this a try sometime.

Great info, waterhead. Thanks!

I also had an audio sync problem when transcoding recorded HDTV shows using Nuvexport in Mythbuntu 8.04. While investigating this problem, I did a lot of experimenting with Nuvexport and FFMpeg.

Nuvexport on my system was set to transcode all recorded TV (HD and SD) to MP4 files using ffmpeg. I found that ffmpeg had a problem with transcoding HDTV shows with Dolby Digital 5.1 encoded audio which would cause a severe audio sync problem during playback. Dolby Digital 2.0 HDTV shows transcoded fine. (I hope this isn't backwards, I no longer have the system to confirm). I downloaded bleeding edge SVNs of ffmpeg and couldn't find a solution, but I didn't go as far to submit a bug report.

Another piece of information - I also remember that I didn't start having this problem until I switched from a PCI Air2PC tuner to a HDHomerun tuner. I can only guess that the HDHomerun may be recording more than one audio stream that ffmpeg couldn't deal with. I think the Air2PC had a MythTv config option to only record one audio stream.

You can verify my finding by transcoding your recorded HDTV shows manually using FFMpeg. I suggest you record 1 minute of each type of audio encoded tv show (Dolby 5.1 & 2.0) to make the transcoding go faster. You can verify the type of audio in the recorded .mpg using the following command:

ffmpeg -i your_recording_file.mpg

You can transcode to MP4 using a ffmpeg command line something like this:

ffmpeg -i your_recording_file.mpg -vcodec mpeg4 -s 640x480 -b 1500k -acodec aac -ar 48000 -ab 128k -f mp4 test.mp4

I always transcoded to MP4 formats because I could also load it on my ipod


Tim

I've been searching for a way to simply transcode my ATSC transport streams to Bluray.

So far I've confirmed three things:
- that the mythnuv2mkv.sh script doesn't work as a user job nor on the command-line;
- that Myth's Transcode mpeg4 function uses ffmpeg to convert to DiVX 1920x1088 10bpp 29.970 fps, audio mp3 48000 Hz, 2 ch, s16le, 128.0 kbit/8.33% (ratio: 16000->192000);
- that ffmpeg can indeed convert to H.264 using libx264, but how to force this into Myth is a mystery.

I have not been able to confirm what audio formats to convert to in order to preserve 5.1 & 7.1 Bluray-compatible, nor what bitrate I should use for a quality recording. I guess just transcoding all formats present would be fine.

And Bluray 24f/s does not seem like it could possibly play without flicker.