Optimum MPEG-2 capturing bitrate for sattelite TV?

[SeanG]

I've read that 6.9M-bits/sec is the highest effective bitrate of an MPEG-2 even if capturing at 10M-bits/sec from a TV signal...
I've tested this but - maybe its my imagination - captures at 7Mbits look fuzzier than captures at 10Mbits.

If 10M-bits/sec capturing produces a clearer, more accurate image, I'll record these to DVD. However, at 10M-bits/sec, an hour of video (with 256K-bits/sec Audio) is around 4.5GB, so this occurs to me: published DVD movies have around 2 hours of "DVD quality" video on them, so what should be done to these MPEG-2 files to fit more than an hour of video onto a 4GB DVD-R while retaining sattelite-TV quality?

[FOO]

That rate may reflect what the satellite downlink rate is. I dunno
If the video is really high quality, it is unlikely that a
capture to MPEG2 will do it justice because the encoder just
can't do an adequate job in real time.

Unless you have unusual expensive equipment, the way to get the best
is to capture an AVI with Huffyuv or MJPEG codecs and encode it
later to MPEG2 with a multi pass MPEG2 encoder like TMPGenc or CCE

Commercial DVDs seldom get near the 9.8 mbps limit and even then
they have 9 G of space while a DVDR only has half of that

The good news is that a "normal" movie will fit on a DVDR and look
as good as the TV can display.

[non-linear]

I think 10Mbps is what networks use when they feed programming to their affiliate stations. As far as satellite providers, it all depends on the service.

I think most wouldn't go past 5mbps (the providers have to compress a lot of channels on the available transponder space).

Don't forget, if the satellite signals are digital, then you're going to lose a bit of quality since you're really recompressing a digital signal.

With that said, it's still a good idea to capture the highest settings possible to maintain the best picture quality, especially if you're going to edit and recompress the video anyway.

Personally, I use between 6-8Mbps (depending on the source material). If you have enough hard drive space and can get 10mbps captured without losing any frames, then by all means do it (although, I think that the DVD standard only allows up to 8Mbps anyway).

Also, it's not really fair to compare your results with a commercial DVD since they're mastered from the original material. Even then, I doubt they use any bitrate over 6mbps (probably between 4-5Mbps) when mastering the video to disc.

[SatStorm]

In Europe rarely a station transmits over 6000kb/s, even with full D1 framesize....

If you want to rip DVB transmissions, better do it direct: It is possible with the correct software and hardware. I do it 3 and a half years now!

Look for PCI cards like Hauppague win tv nove, or technisat DVB cards...

[ronnylov]

It is worth mentioning that maximum DVD bitrate is 10 Mbit/s including all audio and subtitle tracks if you want to stay within DVD specifications.

I also agree with satstorm that the best thing is to capture the stream directly using a DVB-S card (if you live in Europe). I capture the mpeg2 stream digitally from cable TV in Sweden using a Hauppage DVB-C card and the bitrate is mostly below 6 mbit/s, normally averages at 4.5 mbit/s. Some channels are at half resolution and 2.6 mbit/s and the quality is still OK.

[SeanG]

I have been capturing the digital-TV stream "directly" - my graphics card has hardware encoding to MPEG-2...

As for recording to .AVI, maybe the settings were high on my testing, but each minute of record time took over a Gigabyte, aside form that, converting hours of video to MPEG-2 isn't much fun. However, my aim is to obtain the highest quality as these 10-Mbit/s MPEG2 captures but with a lower bit-rate, so that 2 hours - not only 1 - will fit onto a DVD-R...

[ronnylov]

I have been capturing the digital-TV stream "directly" - my graphics card has hardware encoding to MPEG-2...

As for recording to .AVI, maybe the settings were high on my testing, but each minute of record time took over a Gigabyte, aside form that, converting hours of video to MPEG-2 isn't much fun. However, my aim is to obtain the highest quality as these 10-Mbit/s MPEG2 captures but with a lower bit-rate, so that 2 hours - not only 1 - will fit onto a DVD-R...

I did not mean a hardware encoder when I said capture the stream directly. I meant direct copy of the digital stream which already is sent as mpeg2 from the satellite, no encoding needed. If you encode with your graphics card you have already converted it to analog before converting it to digital again. But I guess you want to use the equipment that you have already.

To fit 2 hour on one DVD-R your bitrate should be around 4850 kbit/s if you have 224 kbit/s audio. Have you tried half D1 resolution (352x480 NTSC or 352x576 PAL). you'll get lower details (maybe, depends on the source) but better quality at lower bitrates. 2 hours is just about the limit when I capture from an analogue source, longer captures and I select half D1 resolution instead.

[vhelp]

Hi all.

Right now, there is one important issue that is still, currently today, NOT
being addressed when using these Hardware MPEG-2 devices/units.

And that is, IVTC. I've yet to see any store purchased device/unit that
incoprorates this into the MPEG-2 Hardware chip. and, being that I've
own at least one such device, I can safely say that they don't incorporte
such an IMPORTANT feature!! I"ve yet to see this issue brought up in
these Hardware MPEG-2 device topics. So, I'm here, breaking the ice !!

This alone will bring down your quality captures, even if they ARE hardware
assisted. Instead, these devices only capture as is, the stream, and then
re-encodes them. Guess what, you are re-encoding w/ Telecin'ing (assuming
that the source is Film) Tipicle TV shows are either pure Interlace, or
clumsy Telecine work. I guess that it is becuase of this "clumsy" Telecine
work on such sources, that a final decision was made not to incorporate
such a needful feature. Hey, "why not add in a few 'options' and let the
end user be the judge?"

Final thoughts...
If you want the maximum in Satellite TV projects, you should capture ultimiatly
to an AVI, and then you have the full control on how to encode it, but this
time, based on conditions:

* Progressive ...(easiest)
* Pure Interlace ...(fair, unless you're a guru)
* Telecine ...(aka, requires the revers aka, IVTC)
* Ill-regular Telecine ...(aka, requires the revers aka, IVTC w/ lots of work)

The above would be the ultimate maximum in quality. Hardware, imo, is souly
based on user opinion.

That's about it..
-vhelp

[SeanG]

The graphics card I'm using is a GeForce4 MX440 with 8x AGP, 64 MB on board RAM.

I was unaware of direct DVB capturing till mentioned here; can this card do it? Or some special software? If not, and DVB captures look as good or better and has a lower bit-rate than the MPEG-2's I'm making now - so that I can come closer to 2 hours of video per DVD-R, I'm all for buying a capture card that will; which one? I'm recording in NTSC format.

As for .AVI captures, is it just improper settings, or should 1 second consume 70Megs? This seems insane, but that's just about what an .AVI took when I tried it.

[ronnylov]

You'll need a DVB-S capture card to capture DVB directly, but unfortunately most DVB satellites sends to Europe and that's why the DVB-S cards not are very common in USA. Hauppage make some DVB cards. Check if they have one that can receive the sattellite you are watching. I know some people can record HDTV streams in north america but I don't know exactly how they do it. I live in Sweden so I can only receive european channels and we don't have hdtv but we have a lot of normal dvb channels.

Your graphic card can not record the sattellite stream directly, so you need to hook it up to a satellite receiver box and capture the analogue video-out signal from the standalone receiver box. There is some noise in the digital-analogue-digital conversion process and you loose some quality so then you may need a little bit more bitrate to compensate.

The only thing that allows 2 hour on one DVD-R is to use an average total bitrate below 5 mbit/s. If you make mpeg2 with half D1 resolution 352x480 this bitrate will be more than enough to get good quality. The quality should be OK also at full resolution at this bitrate. If you capture to avi file and encode it to mpeg2 then you can use 2-pass VBR encoding to get highest possible quality.

When capture avi you can use different codecs. When I capture with the huffyuv codec I need up to 40 GB to capture one hour in full resolution. The hyffyuv codec is lossless and compress similar to tiff pictures. I get 11-12 MB for one second of AVI. Are you capturing uncompressed avi?
You can also try a mjpeg codec like picvideo. I recommend to check out lukes video guide to laern about analogue video capturing: http://www.lukesvideo.com/

When I capture with my DVB card the mpeg2 stream is recorded in the PVA file format, which contains video and audio in mpeg2 format. I use a software calld DVBControl to record DVB. Other third part software that can be used is ProgDVB or DVBExtreme besides the bundled software that comes with the card. The PVA file need to be demuxed to elementary video and audio streams. This demuxing is made with a software called PVAStrumento, which gives you a mpv and a mpa file. These files can be used directly as source in a DVD-authoring program like DVDlab. After authoring it can be burned as DVD-Video to a DVD-R. The quality is exactly the same as when it was sent from the sattellite because it's copied directly in digital format (just as a DVD-rip to mpeg2, but this is a DVBrip to mpeg2). The bitrate can't be changed when capturing. It's the same bitrate as the satellite broadcast. Normally it is a constant bitrate below 6 mbit/s. No other methods can give better results than the direct DVB stream recording method, because it records the complete video and audio stream that was broadcasted so no information is lost in the conversion process. Using an analogue capture card will capture the same signal after it has been decoded and converted to analogue video signal and then it is converted back to digital again and recompressed. That would be similar to encode a DVD by capturing the video signal from a standalone DVD player connected to an analogue capture card instead of ripping the disc in a DVD-ROM unit. I get a better quality by reencoding my original stream compared to capture it with an analogue capture card and then encode it. And mostly I don't need to reencode it at all.

To learn about DVB capturing I recommend the DVBN forum:
http://forums.dvbnetwork.com/
They have a section about DVB in north america so it's not completely impossible but I guess it's not as easy as in Europe. The good thing is that it is possible to capture in HDTV format in Nortn america which is not possible in Europe... I guess it's a little bit complicated but not impossible.

[energy80s]

Yes, in the UK we also have Digital Terrestrial Television. With the addition of a PCI card I can grab the raw datastream off air and archive broadcast quality TV onto a DVDR disc. The signal is basically an MPEG2 stream and all it needs is re-muxed and it will playback fine on a standalone DVD player. Bitrates vary between 2.5 and 6 Mbps, but as the broadcasters are using high quality Snell & Willcox encoders the picture quality is a damn sight better than what we can achieve on a PC for the same low bitrates. Here's an example of a still frame from a BBC1 programme - I have had to compress it down to get under the 50kb file size allowed to be posted here, so the quality is actually slightly better than this ...



Satellite capture uses a similar procedure and will yield similar quality. Far better and far less hassle than capturing through a TV card.

[lordsmurf]

I've read that 6.9M-bits/sec is the highest effective bitrate of an MPEG-2 even if capturing at 10M-bits/sec from a TV signal... I've tested this but - maybe its my imagination - captures at 7Mbits look fuzzier than captures at 10Mbits. If 10M-bits/sec capturing produces a clearer, more accurate image, I'll record these to DVD. However, at 10M-bits/sec, an hour of video (with 256K-bits/sec Audio) is around 4.5GB, so this occurs to me: published DVD movies have around 2 hours of "DVD quality" video on them, so what should be done to these MPEG-2 files to fit more than an hour of video onto a 4GB DVD-R while retaining sattelite-TV quality?

It's your imagination.

If you're in the USA or Canada, you are on a NDS or Nagra system using DSS or variants of DVB or DVB-II.

DISH and Bellevue use 480x480 at 0.0-9.8 VBR, but almost all of the signal falls in at 2.0-5.0. DirecTV uses 544x480, same bitrates. Resolutions can vary from channel to channel, but those are the ones used most.

Central and South America use DirecTV variants too. Not sure what other services are down there.

We are on encrypted signals and cannot grab the stream direct in the USA or Canada. (Although there are some hacks for DISH using a PVR unit and removing the HD.)

Recently both DISH and DirecTV have been squishing more stations and more AC3 Surround PPV, so the bitrates have been crunched more than normal. They are likely near the 1.0-4.0 spectrum at the moment, but I hope that nonsense ends soon. I like more channels, but not at the expense of quality loss across all channels.

[ronnylov]

Most DVB channels in Europe are encrypted too. The DVB card has a connection for a CAM module with a card reader. I don't know if these can be bought separately for North American encryption systems or if the DVB cards will work at all in America... Some encrytions used in Europe are hacked but they are being replaced to more difficult encryptions now to get rid of the TV pirates. As long as you can get a CAM module that works with your legal subscription card you should be able to use the DVB card.