DivX to SVCD/DVD Bitrate question

[Mozz]

When converting divx to mpeg-2 (svcd or dvd) what bitrate is needed to keep the quality? Is it really necessary to encode at 8000 kbits/s when converting divx with a bitrate at e.g 800 kbits/s?

[ZippyP.]

The bitrate of a divx doesn't directly relate to the bitrate of an mpeg, they use different types of compression. For best quality always use the highest bitrate possible and higher resolution needs higher bitrates... so DVD res. needs higher bitrate than SVCD. You need to decide what bitrate looks good to you as everyone has different levels of tolerance. Hope that helps a bit.

[Mozz]

Thanks. I'm learning new stuff every day

I've experimented with different bitrates and I can honestly say that I don't see any quality loss from 8000 kbits to 3000 kbits when I convert a DivX movie to MPEG-2. Thats why I wonder if maybe the quality can't get any better when the bitrate passes a certain point because the movie can never be better then the source, and the source in this case lost a lot of quality when it was encodet with DivX and that's not coming back when you convert to MPEG-2 no matter how high the bitrate is set. Do you grasp my way of thinking?
What's the compression ratio for MPEG-2 compared to DivX/XviD?

[RabidDog]

What's the compression ratio for MPEG-2 compared to DivX/XviD?

How long is a piece of string?? In my own experience I would say divx/xvid will compress down to 1/6th the size of mpeg2 (for same quality and res) however sometimes you can get 1/12th and still have reasonable quality (with lower res). YPYMAYTYC.

[Mozz]

[quote="RabidDog"]

How long is a piece of string??

Funny
I consider myself as a newbie so please don't tear me a new one if I say something stupid guys

I have no idea what YPYMAYTYC means...

[ZippyP.]

Thats why I wonder if maybe the quality can't get any better when the bitrate passes a certain point

You're right on with that observation. Beyond a certain point the difference is very small. What that point is depends on the source (like a crappy divx or a high quality DVD), your encoding method (CBR or VBR) and the resolution that you choose for your mpeg (VCD,SVCD or full DVD).

[ZippyP.]

I have no idea what YPYMAYTYC means...

I don't either but I can guess. You pays you're money.....

[RabidDog]

zippy gets 10 bonus air miles. you pays your money and you takes your choice.
I would agree that there certainly is a maximim bitrate beyond which no improvement is possible, I would guess 1/3rd the size,(mpeg2 to mpeg4) but in my experience the dif between say 100% quality and 90% will be unnoticed by the average viewer, whilst making a big dif in the filesize.