<br><br><div class="gmail_quote">On Tue, Sep 21, 2010 at 2:33 PM, Bob Sully <span dir="ltr"><<a href="mailto:rcs@malibyte.net">rcs@malibyte.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
> Date: Mon, 20 Sep 2010 15:39:33 -0400<br>
> From: Doug Vaughan <<a href="mailto:r.d.vaughan@rogers.com">r.d.vaughan@rogers.com</a>><br>
> Subject: Re: [mythtv-users] Transcoding HD-PVR Recordings<br>
<div><div></div><div class="h5">><br>
> John and Kirk,<br>
> I regularly edit and transcode HDPVR recordings. There are some<br>
> restrictions which may not suit you but here is what I do.<br>
><br>
> 1) I locked my STB to 1280x720p output. This keeps the recording size<br>
> down but allows me to reliably use a video editor.<br>
> 2) I use a compiled version of Avidemux 2.4 as I found at least the<br>
> Ubuntu packaged version could not handle the audio AC3 tracks. Avidemux<br>
> has not worked for me with 1920x1080i HDPVR recordings. I have reliably<br>
> edited up to 8Gb files if the 1280x720p restriction is adheared to.<br>
> Although I rarely record more than 6Gb HDPVR file.<br>
> 3) I edit the HDPVR recording as needed then save as an avi with copy<br>
> audio and copy video settings.<br>
> 4) I run a ffmpeg copying the audio and video tracks to change the<br>
> container from avi to mkv. This also sets a seek table that reliably<br>
> works with the MythTV internal player.<br>
> 5) If you want to transcode the mkv file use HandBrake either the GUI or<br>
> the CLI. I have several presets for various sizes of transcoded video.<br>
> Handbrake already has iPod presets that you can use. I transcode the<br>
> output to mkv files. If you want to use the cli then you can cut and<br>
> paste their iPod presets from the GUI. That was my starting point when<br>
> building my customized presets.<br>
> 6) Occasionally the audio can be out of sync which I correct with a<br>
> feature of MKV File Creator GUI. MKV File Creator will not accept the<br>
> HDPVR recordings directly you need to at least change their container<br>
> type with a ffmpeg copy.<br>
><br>
> As I can write python and bash scripts, outside of the manual editing or<br>
> audio resync, the whole process has been automated. I even initiate the<br>
> process as a right click script in Nautilus. The transcoding occurs as<br>
> an overnight cron job.<br>
><br>
> This would not be what everyone would want but has worked well for my<br>
> needs almost two years now.<br>
><br>
> Doug<br>
<br>
</div></div>Doug:<br>
<br>
This is exactly what I do, with pretty good results. I do a two-pass<br>
ffmpeg to transcode the HD-PVR file to an .avi, then use avidemux to cut<br>
out the commercials. Two questions:<br>
<br>
(1) No matter how I tweak the HD-PVR settings (right now set to 11M bit<br>
rate), usually a 1-hr raw HD-PVR recording runs about 1.7GB in size (also<br>
at 720p from the STB). The quality seems VERY good, however. I would<br>
think that if the bitrate was low that the quality would be poor, but this<br>
isn't the case - but the file sizes imply that it it IS low. How are you<br>
tweaking your HD-PVR settings? Mine are set at boot time via the settings<br>
in the wiki.<br>
<br>
(2) Step 4: Can you give us the syntax of your ffmpeg command to convert<br>
your .avi file from avidemux into a .mkv? I have noticed occasionally<br>
that the audio will be out of sync on playback until I hit the back- or<br>
forward-arrow key, then it's fully in-sync for the remainder of the<br>
playback.<br></blockquote><div><br>Step 4: I believe mkvmerge should be able to do this too. <br></div></div>