<br><br><div><span class="gmail_quote">On 1/19/07, <b class="gmail_sendername">Steven Adeff</b> <<a href="mailto:adeffs.mythtv@gmail.com">adeffs.mythtv@gmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On 1/18/07, ryan patterson <<a href="mailto:ryan.goat@gmail.com">ryan.goat@gmail.com</a>> wrote:<br>> On 1/18/07, Steven Adeff <<a href="mailto:adeffs.mythtv@gmail.com">adeffs.mythtv@gmail.com</a>> wrote:<br>
> ><br>> > On 1/18/07, ryan patterson <<a href="mailto:ryan.goat@gmail.com">ryan.goat@gmail.com</a>> wrote:<br>> > > I'm experimenting with the transcoding my over the air HDTV recordings<br>
> to<br>> > > mpeg-4 to save hard drive space. I enabled transcoding but didn't<br>> change<br>> > > any of the default bitrate values. I did enable the "scale bitrate<br>> > > according to capture resolution" option. I am recording OTA HDTV with a
<br>> > > HDhomerun unit. Here are my results from the first show I transcoded:<br>> > ><br>> > > Channel: CBS<br>> > > Title: Racheal Ray<br>> > > Original size: 6.8GB<br>> > > Transcoded size:
6.3GB<br>> > ><br>> > > Does this look like usual space savings from transcoding? Half a gig is<br>> a<br>> > > lot, but honestly I was expecting more. It saved less then 7.5% of the<br>> > > original file size. Basically if I transcode everything I can have 107
<br>> > > hours of recordings on a given hard drive size instead of 100 hours. I<br>> > > think it would be better to save the cost of the electricity used to<br>> > > transcode and buy a larger hard drive.
<br>> > ><br>> > > I didn't cut the commercials. I know that would have saved more space,<br>> but<br>> > > I am not interested in archiving shows. I just watch once and then<br>> delete.
<br>> > > And I don't trust the commercial flagging enough to cut without manually<br>> > > checking the cuts first.<br>> > ><br>> > > Am I missing something? Do I need to adjust some bitrate settings to
<br>> get<br>> > > better compression?<br>> ><br>> > Depends on how much your willing to loose in quality.<br>> > Basically, xvid will give you no size advantage over mpeg2 for HD<br>> > recordings. mpeg4 (without h264) was not designed for larger
<br>> > resolution higher bitrate encodes, thats where h264 comes in. Now, the<br>> > best way to save space without compromising quality is use an inverse<br>> > telecine filter and reencode to mpeg2 at the same Q level as the
<br>> > original "frame", this should give you very little loss in quality<br>> > while saving about 15% of file size.<br>> ><br>> > One way to save space for 1080i broadcasts is to resize them to 720p,
<br>> > you won't notice much loss in detail because most 1080i broadcasts are<br>> > noisy anyway.<br>> ><br>> > or use x264 with mencoder or similar. this with inverse telecine can<br>> > net you perhaps 30% savings with about equal quality.
<br>> ><br>> > so as you can see, transcoding HDTV is really only useful for<br>> > archiving. with the price of 500GB drives under $150 now, your better<br>> > off just buying one of those suckers.
<br>><br>> So how do I change to using mpeg4 with h264? I didn't see that option while<br>> configuring transcoding in the frontend or backend. Is there a flag I<br>> should set for the transcode command?
<br><br>right now its not supported.</blockquote><div><br>Thanks. I tried transcoding some more shows last night with the same settings. One saved a gig of space for a one hour show. This was almost a 14% savings. I'll continue experimenting.
<br><br>I think the transcoding would be more useful if I had a lower resolution TV. My display's native resolution is 1080p and accepts that for input. So I'm not too interested in down sampling the resolution of my recordings.
<br> </div><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">--<br>Steve<br>Before you ask, read the FAQ!<br><a href="http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions">
http://www.mythtv.org/wiki/index.php/Frequently_Asked_Questions</a><br>then search the Wiki, and this list,<br><a href="http://www.gossamer-threads.com/lists/mythtv/">http://www.gossamer-threads.com/lists/mythtv/</a><br>Mailinglist etiquette -
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