movie length into a avchd dvd9

[supersam]

i have a 2hr 50 min movie that i am planning on converting to avchd and be burned into a dvd9. my question is this if i compress this almost 3hr movie into a dual layer will the compression be noticeable to the point where it would be no point in compressing the movie in the first place? I love quality movies so i only go as far as 2hr 10min movies or so....never a 2hr 50min movie, so im kinda skeptical as to whethever the quality difference wont be that noticeable since i do know the x264 has superb compression ratios . I have been making avchds for about more than a year now, but this is the first time where im contimplating on whethever i should go for compression to fit into a dvd9 or have a set at fixed bitrate and see where the file size lands..lol. So, guys let your voice be heard and give me ur opinon on this matter.

[guns1inger]

It is one of those "suck it and see" cases. If you are resizing down to 720p then it will most likely look pretty good, and certainly far better than DVD. Will it look as good as the original 1080p footage (assuming that is what the original is) ? Probably not.

The questions that only you can answer are

1. Will 1080p footage look as good as 720p footage at the same bitrates ?
2. Is the quality of either acceptable ?

I would suggest you encode a short representative sample at 1080p and 720p, using the same bitrates that you would have to use for the full movie, and do a comparison on your TV.

[poisondeathray]

Impossible for anyone to answer and too subjective. What might be "awesome" for someone might look like "crap" to someone else

The source complexity is important here. A 3hour slow "love story" will compress very differently than a 3hour explosion packed "action movie". And you haven't given a hint of any details other than running time.

[supersam]

well the movie in question is Gladiator. It has its moments of action packed arena fights and then slow verbal scenes. so yeah ur right and action packed movie will look like crap compared to a 3hr movie filled with drama only.and i knew i was gonna get those kinds of answers lol...i was afraid of that. but then again one must take the leap of faith to get alot in return or however that goes...lol. well my input source is 1080p and i have no plan on resizing to 720p as none of my other movies have been resized. I guess I just have to wait and see if the compressed movie will look as good as the original. for me once i start seeing artifacts on my screen then it becomes annoying so yeah i am kinda picky on quality, and i have yet to encounter that problem with my avchd discs. I guess i just have to be patient and see what kind of results i get with my dated pc, which is why i was contimplating on whether i should spend a day encoding it and see that the time spent on it was not even worth it. If i have new machine i wouldnt have no problem in doing another encoding option. but yeah im gonna do a sample clip using the settings for a 2 pass locked on a 8150mb file and a fixed 2 pass bitrate and see which results will be passable by my eyes. thanx for the advice gun slinger.

[guns1inger]

I can tell you now that it will not look as good as the original. You can take that for granted given how much you will have to compress it by.

You won't be able to do a sample encode to a fixed file size of 8150MB as the bitrates will be way too high. You can only do a 2-pass VBR encode (or CBR if you are crazy) and see how it comes out.

[supersam]

I had a feeling i was asking for way too much out of this movie to fit into a dvd9 givin that its almost 3hrs long and has quite a bit of action packed scenes. I guess I have no choice but to go for a fixed bitrate settings which in the end will still give me a smaller file size than the original though so i can save it to my ps3 hdd and view it from there. This will probably be the only movie that will give me this delima..lol

[fritzi93]

Yeah, try it and see. So how big is your display and how sharp are your eyes? :P

My own opinion is it *may* be hard to tell the difference, depending of course on how much action, etc., is in the video. [EDIT: As I was typing you posted that the movie in question is "Gladiator".]. That much compression should be okay on a DVDR-DL, also known as BD9.

An example: When I started doing AVCHD, I did several tests to try to see at what bitrate degradation became unacceptable (to me) on a 47" 1080p LCD. One of the movies so tested was Prince Caspian, about 2 hours, 25 minutes, and compressed to fit on a BD5 (single layer). Movie only, 1080p, audio re-encoded at 448 kbs. Bitrate was ~ 3,700. I used BDRB.

Artifacting was sometimes noticeable when the camera was moving. I expected shadowy backgrounds to be more prone to blocking (like you see on over-compressed MPEG2), but it wasn't particularly. Oddly, though, moving water had a very unnatural look to it. There was also something hard to describe about occasional noise in the video, kind of a grainy, desaturated look to parts of the picture, usually confined to a small area. It was there then poof! gone.

Trying again at 720p produced a perfectly acceptable re-encode.

For my purposes, H.264 at 4,500 kbps is good enough (1080p) for almost all movies. It can go a bit lower, depending. I mean for professionally done movies, be it noted.

What's good enough for you though is, again, something you'll have to try and see.

Good luck.

[guns1inger]

Personally, I would rather have a better quality 720p version that gets upscaled by the player (in my case a PS3) than have a lower quality 1080p version squeezed into the same space.

[supersam]

yeah one man's perception of "good" quality is another man's "bad" quality sort of speak. I heard on other places ....a looong time ago that some people where re-encoding Apocalypto to fit in a BD5 with pretty good reults and that was a quite a long movie. So i figure I would have no problem putting a 3hr movie into a BD9, but then again I dont want to waste a full day on my slow machine only to find out that the quality wasnt passable by my standards. But who knows I might just do it to see what my limits are as far as quality. That way in the future I know I wont even think twice about encoding a almost 3hr movie into BD9. I will just do a fix 2 pass bitrate and the file size land where it may. Plus almost all of my avc files are stored in my ps3 which look pretty damn good when played from there.

[guns1inger]

If you use a bitrate calculator then there is no guess work on file size. A 2-pass VBR encode to correct bitrate will hit your file size target.

Only if you do quality based encoding is filesize up for grabs.

[supersam]

For almost all of my avc encoding files i use xvid4psp which gives me some superb quality results and it also gives you a file size for whatever bitrate you want to use. But I guess putting that big of a file into dvd9 is just asking for too much in other words huh? I may just do a 2 pass fix bitrate encoding and just be content with it.

[guns1inger]

I don't know what you mean by "fixed bitrate encoding". You have three choices.

1. VBR (Variable BitRate) encoding. You give the encoder a maximum and minimum value to work with, and an average value that it needs to achieve. The encoder allocates the bitrate as needed across the length of the video based on the three parameters entered. Usually done with 2 passes. Produces a predictable file size.

2. CBR (Constant BitRate) encoding. You give the encoder a bitrate, and it encodes the entire video at that bitrate. Scenes with no action get more bitrate than needed, scenes with lots of action may not get enough. Again, file size is predictable.

3. Quality based encoding. You tell the encoder what level of quality you want (usually a number - for H264 it is usually between 22 and 16), and the encoder tries to keep that level of quality. Actual bitrate and file size vary based on the video and are not predictable.

The term "fixed bitrate" is pretty meaningless. Semantically it comes closest to CBR encoding, however that would give you a predictable file size. What you are describing seems to be Quality based encoding, but then there is no "fixed bitrate".

You can very quickly test the quality of Xvid4PSP's fixed size (is this what you are talking about ?) encoding by doing a 2-pass encode on a sample of your video using the same average bitrate that Xvid4PSP would be using. In the case of your 2:50:00 movie, 5005 kbps would do the trick. If you like the quality, encode the whole thing. If you don't, do a quality based re-encode instead.