XVID Pleased with Widescreen not with Full Screen

[crash447]

I have been using avi files compressed with XVID much more lately and have determined that I am almost always satisfied with widescreen videos, but more or less never with full screen videos. I have downloaded some widescreen hour tv shows that are a 350mb file and I have encoded some of my movies to files between 700mg and 1gb and I am satisfied with basically all of them. Actually I am really pleased.

I have also downloaded some full screen half hour tv shows and converted many others into files between 175mb and 250mb lately I have been using 250mb file sizes, but I am still not satisfied it seems. At 250mb they are much better, but still seem kind of jerky. I am using AutoGK and using two pass XVID to get the desired file size.

I have read that a larger bitrate is required for full screen shows, but am I just still not using high enough of a bitrate.? I guess I was thinking that since a 350mb file for an hour show is pleasing in Widescreen then surely a 250mb half hour show would be pleasing in full screen.

I am just looking for some input since I am trying to convert all of my shows at the moment and wanting to develop a good system. Thanks for any help.

John

[Baldrick]

What video frame size/resolution are you using?
And your source is from a DVD right?

[crash447]

I have tried doing quite a bit of reading and read somewhere that it was best to let AutoGK choose the resolution itself. Most of the time it is around 512x384 or 496x368. I am also viewing these on a 32" standard tv.

Thanks again,
John

[mats.hogberg]

What counts is bit per pixel, all other things equal. Wide screen and full screen doesn't say much.

it is around 512x384 or 496x368.

For what? Full screen encodes? Wide screen encodes? Both?

/Mats

[crash447]

Forgot to say that yes my source is DVD.

Thanks,
John

[crash447]

The 512x384 and 496x368 is for the Full Screen encodes.

[mats.hogberg]

...and the wide screen?

/Mats

[crash447]

Widescreen 624x352

[mats.hogberg]

Well, since the frame sizes for your full screen encodes are smaller than your wide screen, if anything they'd require lower bitrates.
OTOH, "jerkiness" isn't a sign of bitrate starvation - the differences you see must be something else.

/Mats

[FulciLives]

I have read that a larger bitrate is required for full screen shows, but am I just still not using high enough of a bitrate.? I guess I was thinking that since a 350mb file for an hour show is pleasing in Widescreen then surely a 250mb half hour show would be pleasing in full screen.

There is faulty logic in that statement.

A Full Screen source needs MORE bitrate (not LESS bitrate) than a WideScreen source. Why? Full Screen is a higher resolution because the entire screen is image whereas in WS only some of the entire screen is image.

For best quality a Full Screen DVD source should be encoded at 640x480 but that will need a lot of bitrate (i.e., a big file size). If you want to use a lower bitrate (to get a smaller file size) then you can lower the resolution to something like 512x384 for instance. But then you sacrifice resolution only to get a smaller file size.

- John "FulciLives" Coleman

[crash447]

I have read that a larger bitrate is required for full screen shows, but am I just still not using high enough of a bitrate.? I guess I was thinking that since a 350mb file for an hour show is pleasing in Widescreen then surely a 250mb half hour show would be pleasing in full screen.

There is faulty logic in that statement.

A Full Screen source needs MORE bitrate (not LESS bitrate) than a WideScreen source.

- John "FulciLives" Coleman

I don't think that is a faulty statement, I said the same thing you said in that a LARGER bitrare is required for a full screen source. Maybe the confusion came from my statement comparing half hour and hour shows. It just happens that my widescreen shows are an hour long and my full screen shows are full screen, so I am already using a larger bitrate for full screen shows because I know they need a larger bitrate.

[FulciLives]

OK I missed the hour long / half hour long part of that statement.

I would like to point out that the "on-line community" likes to encode hour long HDTV shows (often 1.78:1 widescreen) at 350MB file sizes. However you will find compression artifacts especially at times of "high movement". The file size is picked for bandwidth purposes (i.e., to minimize) while still retaining some level of quality but by no means should that be a desirable target when doing your own stuff for yourself.

In short 350MB is not enough space for an hour long TV show (and yes I realize that is really like 43-44 minutes after TV ads are cut).

You need to raise your expectation of quality. In other words you need to raise your file size limits. With the proper resolution (Full Screen being 640x480) and with the proper bitrate a MPEG-4 back-up of a DVD or HDTV broadcast should look pretty much like DVD quality and not all small and pixelated.

- John "FulciLives" Coleman

[crash447]

Thanks for your input. I really appreciate your help in this, however I guess I am still a little confused on what I need to raise my expectations/file size to. I do see artifacts at times in 350mb downloads and other files I have encoded myself, but for the most part I am still more pleased than the full screen encodes I am doing myself.

In my view in encoding at 250mb for a half hour that is equal to 500mb for a full hour. I have raised the level significantly in my mind, but I understand that might not be the case. I guess I am trying to figure out what a decent file size or bitrate would be for a 640x480 encode. I know that will ultimately be up to me, but hearing what others use might help me get started.

I would also like to point out with these 250mb encodes at 640x480 or a smaller resolution that I mentioned earlier in this post that I am not seeing anything pixelated, it is jerkiness. I have looked into the frame rate, but this doesn't seem to help either.

So I guess I have two questions, #1 what is a decent bitrate or file size for a 22 minute TV show Full Screen at 640x480 and #2 if bitrate is not the cause of the jerkiness then what would be the cause?

Thanks,
John

[FulciLives]

So I guess I have two questions, #1 what is a decent bitrate or file size for a 22 minute TV show Full Screen at 640x480 and #2 if bitrate is not the cause of the jerkiness then what would be the cause?

Thanks,
John

Answer to question #1:
The bitrate will vary depending on the content of the video. MPEG compression is affected by many factors one of which is movement. The more movement in the video (be it camera movement or movement within a still shot) the harder it will be to compress and therefore the more bitrate will be needed. Other things also affect how much bitrate is needed such as the resolution (more needs more) and things like picture properties (the "cleaner" the image the easier to compress and dark images tend to compress better than bright images).

So unfortunately you can't exactly pinpoint what bitrate to use based on just resolution and running time means is more a function of size than bitrate but file size is how autoGK determines the bitrate.

When you run autoGK it prepares the source (if a DVD it creates a D2V project file and demuxes the audio and subtitles and blah blah blah) and then it runs a comp test in order to determine the compressibility based on the file size you have picked. It then returns a percentage.

When I am making my own MPEG-4 files with autoGK (I use XviD and enact the MTK/SIGMA stand alone compatibility option as that "fits" my MPEG-4 hardware player) I try to get a comp test value of 90% or better. If it is less than 90% then I stop the process and raise my file size and then start over again. Sometimes I may have to do that only once or twice or more before I find the "right" file size for that particular video. After a while you do tend to get the hang of it.

Answer to question #2:
The jerkiness could be due to the material being interlaced. When you have interlaced NTSC then autoGK will attempt to perform an IVTC and sometimes this works really well and sometimes it does not. You have an option inside the advanced options (CTRL-F9) to force an IVTC or to force DEINTERLACING. Sometimes it is better to force DEINTERLACING but it probably is better to try IVTC first and if that doesn't work then do it again and force DEINTERLACING.

But even when IVTC is not possible and you must DEINTERLACE ... well ... even then the results are not "perfect" because you end up with 29.970fps progressive and that can look a bit weird especially on a purely progressive display such as a computer monitor (I find that 29.970fps progressive MPEG-4 files look OK to me on my HDTV).

Unfortunately that is the nature of NTSC and MPEG-4 ... i.e., NTSC will sometimes be interlaced in such a way that requires DEINTERLACING resulting in 29.970fps progressive because MPEG-4 as we "know it" does not traditionally handle 29.970fps interlaced video. Well actually you can supposedly make a 29.970fps interlaced MPEG-4 but my understanding is that it doesn't really work so well and autoGK does not account for that type of creation anyways.

- John "FulciLives" Coleman

P.S.
If you still have the autoGK log from one of these "jerky" encodes it would benefit you if you could post it here. That way I can see if it tried to IVTC or if it DEINTERLACED it or whatever.

[crash447]

John,

Thanks for the help and sorry it took so long for me to reply. I just haven't had time to try some of this, however I did realize that most of my full screen encodes were getting Comp % in the 30's so that was making me think they definately needed more bitrate. I haven't gotten a chance to test that yet, however I did try to encode a few episodes of a show that was widescreen last night and thought I would ask for some help on that.

My encodes were going fine and then all of the sudden I have one that looks horrible. It is extremely jerky. I went back to the last two log files and noticed the bad looking one was recorded with a higher bitrate and determined to be HYBRID, where the good looking one was a lower bitrate and determined to be FILM. They both came off of the same disc and were just two different episodes. I also want to point out that I tried Target Quality this time just to get a feel for a higher percentage. Here are the two log files.

#1 the Bad Encode

[11/30/2006 10:29:25 PM] AutoGK 2.27
[11/30/2006 10:29:25 PM] OS: WinXP (5.1.2600).2
[11/30/2006 10:29:25 PM] Job started.
[11/30/2006 10:29:25 PM] Input file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_01_0.IFO
[11/30/2006 10:29:25 PM] Output file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\03-Meet John Smith.avi
[11/30/2006 10:29:25 PM] Output codec: XviD
[11/30/2006 10:29:25 PM] Audio 1: English AC3 2ch
[11/30/2006 10:29:25 PM] Subtitles: none
[11/30/2006 10:29:25 PM] Format: .AVI
[11/30/2006 10:29:25 PM] Target quality: 65%
[11/30/2006 10:29:25 PM] Custom resolution settings: maximum width of 624 pixels
[11/30/2006 10:29:25 PM] Custom audio settings: CBR MP3 with bitrate: 128Kbps
[11/30/2006 10:29:25 PM] Standalone support enabled: ESS
[11/30/2006 10:29:25 PM] Started encoding.
[11/30/2006 10:29:25 PM] Demuxing and indexing.
[11/30/2006 10:30:04 PM] Processing file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_01_1.VOB
[11/30/2006 10:30:04 PM] Processing file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_01_2.VOB
[11/30/2006 10:30:04 PM] Source resolution: 720x480
[11/30/2006 10:30:04 PM] Found NTSC source.
[11/30/2006 10:30:04 PM] Source aspect ratio: 16:9
[11/30/2006 10:30:04 PM] Color correction enabled.
[11/30/2006 10:30:04 PM] Analyzing source.
[11/30/2006 10:34:46 PM] Source has percentage of interlacing in motion areas: 40.60
[11/30/2006 10:34:46 PM] Source has percentage of telecined patterns: 93.30
[11/30/2006 10:34:46 PM] Source has percentage of progressive patterns: 0.94
[11/30/2006 10:34:46 PM] Source has percentage of interlaced patterns: 5.76
[11/30/2006 10:34:46 PM] Source is considered to be hybrid (mostly FILM).
[11/30/2006 10:34:46 PM] Looking for optimal hybrid thresholds.
[11/30/2006 10:35:50 PM] Found threshold of: 1.90
[11/30/2006 10:35:50 PM] Output will contain 61242 frames
[11/30/2006 10:35:50 PM] Decoding audio.
[11/30/2006 10:36:38 PM] Normalizing audio.
[11/30/2006 10:37:28 PM] Encoding audio.
[11/30/2006 10:44:05 PM] Running single pass encoding.
[11/30/2006 10:44:05 PM] Writing the following script to C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\agk_tmp\03-Meet John Smith_movie.avs
================================================== =========
LoadPlugin("C:\PROGRA~1\AutoGK\DGMPGDec\DGDecode.dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\autocrop.dl l")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\decomb.dll" )
LoadPlugin("C:\PROGRA~1\AutoGK\filters\ColorMatrix .dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\RemoveGrain SSE3.dll")

movie = mpeg2source("C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\agk_tmp\03-Meet John Smith.d2v")
cropclip = autocrop(movie,mode=0,wmultof=4,hmultof=4,samples= 10,aspect=0,threshold=34,samplestartframe=0,leftad d=0,rightadd=0,topadd=0,bottomadd=0)
fixed_aspect = 1.18518518518519
c_width = width(cropclip)
c_height = round(height(cropclip) / fixed_aspect)
input_par = float(c_width)/float(c_height)
input_par = (input_par > 1.4) || (input_par < 1.25) ? input_par : (4.0/3.0)
out_width = 624
out_height = round(float(out_width) / input_par)
hmod = out_height - (floor(out_height / 16 ) * 16)
out_height = (hmod > 4) ? (out_height + (16 - hmod)) : (out_height - hmod)
new_aspect = (float(out_width) / float(out_height)) / fixed_aspect
Telecide(movie,order=1,guide=1,post=2).Decimate(mo de=3,threshold=1.9)
autocrop(mode=0,wmultof=4,hmultof=4,samples=10,asp ect=new_aspect,threshold=34,samplestartframe=0,lef tadd=0,rightadd=0,topadd=0,bottomadd=0)
LanczosResize(out_width,out_height)
RemoveGrain(mode=2)
ColorMatrix("Rec.709->Rec.601",opt=0,hints=false)
================================================== =========
[11/30/2006 11:45:39 PM] Duration was: 1 hour, 1 minute, 33 seconds
[11/30/2006 11:45:39 PM] Speed was: 16.58 fps.
[11/30/2006 11:45:39 PM] Job finished. Total time: 1 hour, 16 minutes 13 seconds


#2 The Good Encode

[11/30/2006 11:45:40 PM] AutoGK 2.27
[11/30/2006 11:45:40 PM] OS: WinXP (5.1.2600).2
[11/30/2006 11:45:40 PM] Job started.
[11/30/2006 11:45:40 PM] Input file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_02_0.IFO
[11/30/2006 11:45:40 PM] Output file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\04-The Wrath of Con.avi
[11/30/2006 11:45:40 PM] Output codec: XviD
[11/30/2006 11:45:40 PM] Audio 1: English AC3 2ch
[11/30/2006 11:45:40 PM] Subtitles: none
[11/30/2006 11:45:40 PM] Format: .AVI
[11/30/2006 11:45:40 PM] Target quality: 65%
[11/30/2006 11:45:40 PM] Custom resolution settings: maximum width of 624 pixels
[11/30/2006 11:45:40 PM] Custom audio settings: CBR MP3 with bitrate: 128Kbps
[11/30/2006 11:45:40 PM] Standalone support enabled: ESS
[11/30/2006 11:45:40 PM] Started encoding.
[11/30/2006 11:45:40 PM] Demuxing and indexing.
[11/30/2006 11:46:17 PM] Processing file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_02_1.VOB
[11/30/2006 11:46:17 PM] Processing file: C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\VTS_02_2.VOB
[11/30/2006 11:46:17 PM] Source resolution: 720x480
[11/30/2006 11:46:17 PM] Found NTSC source.
[11/30/2006 11:46:17 PM] Source aspect ratio: 16:9
[11/30/2006 11:46:17 PM] Color correction enabled.
[11/30/2006 11:46:17 PM] Analyzing source.
[11/30/2006 11:51:06 PM] Source has percentage of interlacing in motion areas: 41.12
[11/30/2006 11:51:06 PM] Source has percentage of telecined patterns: 99.49
[11/30/2006 11:51:06 PM] Source has percentage of progressive patterns: 0.51
[11/30/2006 11:51:06 PM] Source has percentage of interlaced patterns: 0.00
[11/30/2006 11:51:06 PM] Source is considered to be FILM.
[11/30/2006 11:51:06 PM] Output will contain 61321 frames
[11/30/2006 11:51:06 PM] Decoding audio.
[11/30/2006 11:51:56 PM] Normalizing audio.
[11/30/2006 11:52:43 PM] Encoding audio.
[11/30/2006 11:59:17 PM] Running single pass encoding.
[11/30/2006 11:59:17 PM] Writing the following script to C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\agk_tmp\04-The Wrath of Con_movie.avs
================================================== =========
LoadPlugin("C:\PROGRA~1\AutoGK\DGMPGDec\DGDecode.d ll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\autocrop.dl l")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\decomb.dll" )
LoadPlugin("C:\PROGRA~1\AutoGK\filters\ColorMatrix .dll")
LoadPlugin("C:\PROGRA~1\AutoGK\filters\RemoveGrain SSE3.dll")

movie = mpeg2source("C:\Documents and Settings\HP_Administrator\My Documents\My Videos\VM 3 and 4\VIDEO_TS\agk_tmp\04-The Wrath of Con.d2v")
cropclip = autocrop(movie,mode=0,wmultof=4,hmultof=4,samples= 10,aspect=0,threshold=34,samplestartframe=0,leftad d=0,rightadd=0,topadd=0,bottomadd=0)
fixed_aspect = 1.18518518518519
c_width = width(cropclip)
c_height = round(height(cropclip) / fixed_aspect)
input_par = float(c_width)/float(c_height)
input_par = (input_par > 1.4) || (input_par < 1.25) ? input_par : (4.0/3.0)
out_width = 624
out_height = round(float(out_width) / input_par)
hmod = out_height - (floor(out_height / 16 ) * 16)
out_height = (hmod > 4) ? (out_height + (16 - hmod)) : (out_height - hmod)
new_aspect = (float(out_width) / float(out_height)) / fixed_aspect
Telecide(movie,order=1,guide=1,post=2).Decimate(mo de=0)
autocrop(mode=0,wmultof=4,hmultof=4,samples=10,asp ect=new_aspect,threshold=34,samplestartframe=0,lef tadd=0,rightadd=0,topadd=0,bottomadd=0)
LanczosResize(out_width,out_height)
RemoveGrain(mode=2)
ColorMatrix("Rec.709->Rec.601",opt=0,hints=false)
================================================== =========
[12/1/2006 12:58:44 AM] Duration was: 59 minutes 27 seconds
[12/1/2006 12:58:44 AM] Speed was: 17.19 fps.
[12/1/2006 12:58:44 AM] Job finished. Total time: 1 hour, 13 minutes 4 seconds


So now I was wondering what exactly I might need to look at and what I might need to do. Is FILM interlaced or non-interlaced? Any help on this one would be great.

Thanks,
John

[manono]

Hi-

Although one was detected as film and the other as hybrid, they're enough alike that perhaps the "bad" one could also be treated like the "good" one, as film. If you'd like to try it again, this time forcing it to treat it the same way as it did the "good" one, go into the Hidden Options (CTRL-F9) and check the "Force Normal IVTC..." box:

http://www.autogk.me.uk/modules.php?name=TutorialEN#6

If it doesn't work, when done you'll be looking for a certain jerkiness in places, perhaps the same places where you saw the jerkiness after the first try.

[crash447]

Thanks I bet that will work and I will try it tonight. You know it's funny how sometimes you just miss something the first time you read something, but I read that exact link last night and specifically read about Force IVTC once again and it wasn't near as clear as reading it from your link. I must have been a little sleepy. Thanks again for the help.

John

[FulciLives]

Try to do as manono said but remember that if FORCE IVTC still produces jerky playback that you can try again but select the FORCE DEINTERLACING option.

Doing an IVTC is better IF it works.

DEINTERLACING of NTSC is to be avoided whenever possible but some NTSC sources just will not IVTC well in which case DEINTERLACING becomes the only other option in such a case.

- John "FulciLives" Coleman

[crash447]

I am trying the Force ITVC as I type this, but I was wondering if it would harm anything to leave Force ITVC checked all the time, or just it only need to be used once a file proves to have problems.

Thanks again,
John

[manono]

Yes, you don't want to have that box permanently checked. Sometimes (most of the time), movies are encoded as progressive 23.976 with the proper pulldown flags, and they can be Force Filmed in DGIndex, with no need for the slower full IVTC at all. Other times, if you ever encode any real hybrid or interlaced material, IVTCing would be entirely the wrong thing to do.

[crash447]

Since another post of mine started ending back up at the Interlaced, Deinterlaced, IVTC saga I thought i would bring this post back up since it is more on topic.

My question is if I have a source that actually is Interlaced and I deinterlace it will it cause me any problems in the future? If so where at? On a monitor, standard TV, HDTV, etc. I am just concerned because everything I read is about people saying to stay away from deinterlacing if at all possible.

Thanks again,
John

[mats.hogberg]

"Don't deinterlace" is my take on this too. For TV playback, interlaced is fine. For computer playback, the player software should deinterlace (if necessary) at play time.

/Mats

[crash447]

Thanks so much for the clarification. The more I have read the more I thought this was the right decision. I have watched less than 1% of my files on a monitor over the past five years, so I think I know where I need to go.

Thanks again,
John

[FulciLives]

There is nothing wrong with doing an IVTC if you can do it successfully which of course implies that sometimes when you can IVTC the results are less-than-perfect. Yet when it works it is the way to go.

Doing a DEINTERLACE is different than an IVTC and should be avoided in almost all circumstances although there are times that might call for it.

It boils down to exactly what it is you are trying to do i.e., make a DVD or a MPEG-4 or format conversions etc.

- John "FulciLives" Coleman