[vdr] Compressing VDR recordings without losing quality.
user.vdr at gmail.com
Sat Oct 30 03:50:39 CEST 2010
On Fri, Oct 29, 2010 at 10:59 AM, Tony Houghton <h at realh.co.uk> wrote:
>> The only way to not lose quality is to keep the bitrate high,
>> especially for recordings with a lot of motion. You should encode
>> with constant quality (CRF) set to whatever the minimum quality you
>> want to preserve. You can also reduce the resolution a bit, just make
>> sure to maintain the aspect ratio.
> And don't try to scale interlaced material without using a good
> deinterlacing filter first.
That's a great point, I should have mentioned it but since I didn't,
it's good you did.
>> Bottom line is that you will not
>> get smaller filesizes without making sacrifices. Data is lost with
>> every encoding pass.
> The point of H264 is that it can achieve better quality for a better bit
> rate. Although some quality will be lost by transcoding, you could
> probably halve the file size without making a noticeable difference.
That sounds good when you read the datasheets but real world results
are a bit different. Also, what you're referring to is encoding
comparisons all from a raw source - not mpeg2 vs. the same mpeg2
reencoded in h264. I can't stress enough that there is no magic to be
had here for the reasons in my previous post.
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