[vdr] Compressing VDR recordings without losing quality.

[Tony Houghton]

On 29/10/10 00:28, VDR User wrote:
>> I wonder if there is an easy way to recompress
>> all recordings that are not already H.264 into
>> H.264 files, making them a lot smaller without
>> losing any quality.
>
> 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.

> 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.