On Fri, Oct 29, 2010 at 10:59 AM, Tony Houghton h@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.