So how do I change to using mpeg4 with h264? I didn't see that option while configuring transcoding in the frontend or backend. Is there a flag I should set for the transcode command?<br><br><div><span class="gmail_quote">
On 1/18/07, <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>> I'm experimenting with the transcoding my over the air HDTV recordings to<br>> mpeg-4 to save hard drive space. I enabled transcoding but didn't 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 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, but<br>> I am not interested in archiving shows. I just watch once and then 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 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>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,
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