|
|
|
How do I compress a 20gig video?
|
|
|
mattmattm
Newbie
|
4. May 2009 @ 16:29 |
Link to this message
|
I'm trying to put it on a 4.7g dvdr and I can't find a way to do it.
I want to keep as much quality as possible because it's hd 1080i, and I plan on playing it on a large television.
I might go out and get dual layered dvds so it might only need to be half the size, but I'd like it as small as you can get.
|
|
Advertisement
|
|
|
|
AfterDawn Addict
|
4. May 2009 @ 18:19 |
Link to this message
|
You can't get something for nothing.
Compression induces loss. Period. The loss of quality goes up with the compression ratio.
Loss due to compression is noticable (to me) at about 1.75:1 ratio. That is a 6GB source DVD compressed to fir on a 4.7GB single layer DVD.
What you are trying to get is a 5:1 compression ratio, 2.2 to 1 on DL.
IMHO, You can't do it on a single disk if you want to retain any semblance of quality. I don't even think you could do it with creative editing, stripping out every non-essential function and preserving just the video and audio.
This message has been edited since posting. Last time this message was edited on 4. May 2009 @ 18:35
|
AfterDawn Addict
|
4. May 2009 @ 19:00 |
Link to this message
|
DVD Shrink will compress but not that much and even if it could, the quality hit would be major. Even using 2 DL media would require some shrinking, think they're around 7.9 G. Personally, I don't like them because my player has an issue with the layer break using good media. Make sure your player and writer both support DL and use 2, you might get away with 1 but I doubt it, a few DVD are okay at 50% compression. Have a look at DVD Rebuilder for any compression too and use it's built in encoder unless you have CCE. Edit: i know my typing can be slow but 41 minutes?
This message has been edited since posting. Last time this message was edited on 4. May 2009 @ 19:07
|
AfterDawn Addict
|
4. May 2009 @ 19:22 |
Link to this message
|
DVD Shrink and DVD Rebuilder will only work with DVD compliant files. Not HD files. You will need to convert to DVD standard which will give you a resolution less than half of what you already have.
99% of all problems are between the computer and the chair.
|
AfterDawn Addict
|
4. May 2009 @ 19:38 |
Link to this message
|
|
Did not know, good info.
|
|
XEQtor
Newbie
1 product review
|
4. May 2009 @ 20:11 |
Link to this message
|
Agree with Dailum.
Remember, your source is HD, but your media is SD. There are not many players out there (currently) that will allow you playback HD content stored on an SD media. Mini-BD (or BDMV stored on DVDRs) may work, it may not. If your player allows this, try splitting/cutting them into MULTIPLE DVDR (DL)s, ala Side A, Side B, Side C, D, etc, WITHOUT re-encoding.
However, if you understand compression loss as Dailum said, and still wants to RE-ENCODE to DVD format, use the following as a guide:
Off-hand, if your source is H.264/MPEG-4 AVC, you're better off creating a DVD on DL media. If your source is MPEG-2 based, then you'll stand a GOOD chance of getting it onto a DVDR media.
I shall assume your source is 1920x1080.
1. Multiply your source resolutions, ie, 1920 x 1080. That'll give you the 'dots-per-frame'. A DVD is either 720x480 (NTSC) or 720x576 (PAL). If your source is 30 fps, choose NTSC, if 25 fps, choose PAL. You now have a 'dots-per-frame' for NTSC or PAL. Know that a 4:3 aspect HD may be 1440x1080.
2. Find out what encoding format your source is. HD is usually H.264 (MPEG-4 AVC) based. DVD is strictly MPEG-2. Know that H.264 is DESIGNED to give 2x the quality for the same bitrate of MPEG-2.
3. Determine what bitrate your source is encoded in. Bitrates above 20Mbps is common for HD sources.
Now comes the difficult/confusing part...
Determine the ratio of the HD 'dots-per-frame' versus your DVD's 'dots-per-frame'. Let's assume your HD is 1920x1080 and your DVD is 720x480. You will get a ratio of 6:1.
If both are using the same encoding format, ie, MPEG-2, your DVD should AT LEAST have 1/6 the bitrate of the HD source. Let's assume that the HD source uses 24Mbps bitrate. This means that your DVD should have AT LEAST 4Mbps bitrate just to compete in getting quality which is as close as possible.
Now, if your HD uses H.264, which is DESIGNED to be 2x better for the same bitrate, this means that your DVD should have TWICE the calculated bitrate, viz, 8Mbps, again, just to get close. Remember that DVDs have a MAXIMUM of 9.8Mbps bitrate and you're already near the top...
A. Get a good resizer. I swear by Lanczos Resize (3-Taps and beyond) despite what others claimed. Theory says you're better off using a bi-cubic resizer since you're down-sizing to an MPEG encoder. Whatever, but make sure that your resizer understand how to resize INTERLACED sources which yours is.
B. Get a good MPEG-2 encoder WITH multi-pass encoding capability and with the ability to set a 16:9 flag for 16:9 sources. If your source is 1920x1080, it's almost likely 16:9. If it's 1440x1080 it's prolly 4:3.
C. Resize your HD source down to DVD format and feed it to the encoder. A frame server is handy. Or else, let the encoder do it during (just before) encoding. In the encoder, give it the bitrate you've calculated, set the 16:9 flag if your source is such, AND set the interlace flag for input AND output. Set your encoder to do 2 or 3 pass VBR encoding. Encode to an elementary stream, ie, ignore the audio part - for now.
Always remember the LOSS due to re-encoding. You can up the bitrate if you want, at the expense of a larger file size.
That does it for the video. Now, the audio.
If your source is already in AC3 (Dolby-zzzizital or whatever), you can rip it out from the source and paste it back into the resultant MPEG-2 elementary stream, creating a DVD compliant MPEG-2 system stream.
Or else, you'll have to extract the audio somehow and RE-ENCODE (again, some loss) to an acceptable DVD audio track - AC3 or MPEG-1 Level II.
Some encoders will allow you to do all that at the same time. If this is the case, encode the whole thing to a "DVD System Stream".
After all these, you'll still have to AUTHOR the MPEG-2 to a DVD. Unless your player can play an MPEG-2 file directly, by all means, go ahead.
If you do all these 'properly', there's a high chance that you'll be able to get a DVD DL output that plays 'nicely' on a 42" TV. I'll even consider upping the bitrate during encode to maximize the whole DVD DL in favor of 'as close to original' quality. If you're too cheap for a DL, split it to 2 DVDRs. 5-pass VBR encoding is nice if you have the time I had.
Personally, I've done something similar, to a DL media. I have an upsampling DVD player tho.
Have fun!
XEQ.
|
|
ac_burt
Newbie
|
4. May 2009 @ 20:36 |
Link to this message
|
There are a couple of easy ways to do what you are wanting. One of the is Bd-Rebuilder which will allow you to make a movie only back up of your blu-ray and will allow you to burn the movie in its blu-ray format on a dvd5 or if you want a little better quality you can burn it on a dvd9. Or you can use a program called Bluray 2 DVD Pro and this program will allow you to either make a DVD or an AVC. Although I find that this programs compressions is more obvious than BD-Rebuilder. (PS: BD-Rebuilder is freeware, although if you like it I would recommend making a donation to the creator)
|
|
Advertisement
|
|
|
|
jony218
Suspended due to non-functional email address
|
5. May 2009 @ 23:57 |
Link to this message
|
See if the free mediacoder can open that file. If it can use the h264 codec and convert it. You can adjust the resolution from low res up to 1900x1000. You can try a bitrate of 1600kps or higher.
The h264 codec will give you HD quality.
|
|
