PVR question, software encoding vs. hardware encoding

[iamtrout]

What are the benefits to hardware encoding on a TV tuner card? Is the quality better? How much power and system resources would get hogged if I used software encoding? Would I even have to worry about this if I encoded everything into DiVX, not MPEG?

 

[rbV5]

The benefits are low cpu useage for recording. The quality isn't necissarily better, but with the right software you can get consistently good results when matched with supported hardware. It makes multiple tuner support and more advanced PVR functionality like timeshifting and scheduled recordings more stable and less intensive on your rig.

Software decoding is dependant on the power of your PC, and how well your hardware is supported with your software. The more compressed a format is, and how much filtering you use determines how much resources it will take. Highly compressed formats like Divx and WMV generally require more CPU to encode, basically, the "smaller" you make your file with similar image quality, the more demanding it will be on your system. Less compressed formats require less cpu, and will require more and faster storage space. Uncompressed, or lossless formats are generally more suited for editing.

 

[iamtrout]

But will hardware encoding on the TV Tuner matter if I'm encoding only into DiVX? Most, if not all, hardware encoders only help with the MPEG1/2 encoding. If I only do DiVX, then there isn't any point to get a more expensive PVR with hardware encoding, correct?

 

[rbV5]

Originally posted by: iamtrout
But will hardware encoding on the TV Tuner matter if I'm encoding only into DiVX? Most, if not all, hardware encoders only help with the MPEG1/2 encoding. If I only do DiVX, then there isn't any point to get a more expensive PVR with hardware encoding, correct?

I think Plextor makes a hardware Divx encoder actually, but alot depends on your use. My opinon is that hardware encoder cards work best for PVR duties, and its not just because of the hardware encoder itself. The best PVR softwares I've used simply support hardware encoder cards. If features like scheduled recordings from a good EPG, or multi tuner support are most important, SageTV and MCE 2005 are the best I've used, and they support hardware cards only (for the most part)

If you are just encoding DIVX on the fly in software, then no, a MPEG encoder card won't be the best bet. If you are encoding your files to DIVX to archive after you capture, a hardware card based PVR makes a nice, consistant source of footage to re-encode, but is a more costly solution.

My AIW card on the other hand was a bit weaker in the scheduling end, but supports DIVX capture quite well with a reasonably powerful rig, 2GHz P4 512 MB ram would handle pretty decent compression on the fly with Divx without dropping frames depending on the settings. So software is definately viable on that class of a rig.

 

[THUGSROOK]

DivX is best for PC viewing cause all of the deinterlacing and AA is already done for you during the encoding. a good 2-pass DivX encode can easily be better then a DVD on a PC.

a 2ghz cpu is gonna take some time tho


...and bump!

 

[rbV5]

DivX is best for PC viewing cause all of the deinterlacing and AA is already done for you during the encoding. a good 2-pass DivX encode can easily be better then a DVD on a PC

Hold on there now
Divx can be deinterlaced during encoding using a deinterlacing filter, or it could just be encoded from progressive source material, or it could be encoded interlaced for smoother playback on an interlacing display....just like MPEG-2 for DVD authoring.

Divx can also be better than material on a DVD sure, but only because the quality of video on a DVD is completely dependant on the quality of the source of footage used to author the DVD. Same with a Divx file, the end product depends on the quality of the source and the encoding settings used.

Divx supports up to 720p resolution (or better), while MPEG-2 DVD's currently are limited to 480p and the vast majority are actually 480i, so in that respect...it can be, but MOST Divx files are simply encoded from ripped DVD's and will of course be lower quality than the original DVD.

I'd say, for the most part, while DIVX "can" be better in specific cases, DVD playback on the desktop with the right combination of filters, graphics hardware, and playback software will almost always be superior to DIVX all things being equal.

 

[THUGSROOK]

DVD playback on the desktop with the right combination of filters, graphics hardware, and playback software will almost always be superior

well yea of course. but in their absence DVD will look rather poor.

you obviously know alot about this and i wouldnt dare claim otherwise.
but i have made DivX files that were better then the original DVD, or at least indistingwishable from the original DVD. like you said tho, in the "better" cases the original DVD quality wasnt so great to begin with. it always depends on what you start with.

 

[rbV5]

Divx is a good archiving format (and file trading format) since it has good file size/quality ratio like the other MPEG4 based formats like WMV and XVID, and is now being supported on some DVD players also. You can rip/encode many DVD's to fit on a single CDR, which is a bit less of an issue now with DVDR, but will again become more popular with Divx HD ( check out the demo's here again due to its excellent size/quality ratio.

Hardware "encoding" support would be nice for Divx

 

[craneo]

Remember hardware encoding is usually only done on capture, thus you are limited to real time encoding. This is not a bad thing mind you. But unless your editing software handles your hardware, all your editing will depend on the CPU. The other downside of a hardware encoder is that its usually fixed for one type of codec, which is OK as long as it is one you can live with and hopefully tweek for bit rate, etc.

If all your doing is a pure capture PVR or capture to SVCD/DVD burn, then the advantage of the hardware encoding is to allow you to use a less powerful CPU. But unless you are editing or reencoding, I think a decent software encoder will work just as good as the hardware one in the P4 2.0G machine. Of course, I would not touch the machine while its encoding, but I would not want to be doing something with it much while capturing anyway. Granted the 2.0G P4 machine will be a bit slow if you do any reencoding.

I've capped my Time Warner box's SVideo out with software encode (8500 AIW) to SVCD mpgs and burned them to CDs and they turned out very nice especially from HBO or one of the other movie type channels.

 

[THUGSROOK]

rbV5 ~ just to clarify, my DivX files are always 2 cd files.

they are for personal use only, not trading, so small file size is not important. (other then the fact i want the most quality i can possibly get on 2 cds)

 

[rbV5]

Originally posted by: THUGSROOK
rbV5 ~ just to clarify, my DivX files are always 2 cd files.

they are for personal use only, not trading, so small file size is not important. (other then the fact i want the most quality i can possibly get on 2 cds)

I'll bet HD resolutions wouldn't be (assuming feature length). But, you're right using 2CD's for feature length encodings is required much of the time to keep the bitrate high enough to keep the quality up...even using 2-pass VBR. I have had some very good 1 CD rips however.

 

[THUGSROOK]

yep 2-pass VBR, usually with a 1500+ BR. sometimes as high as 2500 BR for short movies.
720+ res, maybe a lower 640 res if the movie is really long.

some really well encoded short DVDs could do the same and still fit on 1 cd.
no matter how much BR i gave it the file wouldnt get bigger or better ~ gotta love those good DVDs