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Old 11th July 2005, 23:04   #1141  |  Link
SeeMoreDigital
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Quote:
Originally Posted by Wilbert
Interestingly, the MPEG-2 doesn't mention PAR at all. So, a question for Manao, where is the term PAR coming from (if it isn't mentioned in any specs)?
That's right, because Mpeg2 / DVD, in its commercial form only offers 2No SAR sizes (720x576 for PAL or 720x480 for NTSC) and 2No DAR sizes, 16:9 and 4:3. However, the DAR sizes are still calculated using PAR.

People are now used to cropping and re-sizing their MPEG-4 encodes to any old convenient pixel frame size that either exactly or closely represents the movies theatrical aspect ratio. But with the aid of PAR we can now subtly adjust the pixels to match our 2No (DAR) screen sizes.


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Last edited by SeeMoreDigital; 11th July 2005 at 23:09.
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Old 12th July 2005, 02:35   #1142  |  Link
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Regardless of this discussion i will keep the "Sample AR" label coz the cli option is --sar and not --par or --dar ...
When and if the cli option will change name i'll modify vfw accordingly...
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Old 12th July 2005, 05:07   #1143  |  Link
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--- OFFTOPIC ---
Just to add my little grain of sand, as I've said before I think the whole anamorphic thing is just a leftover from the old analog age of fitting a wider picture into a "slimmer" film frame. It is definetly not needed in the digital world, but I do agree that it might save some bandwitdh with little impact on quality.

That said, in my mind it is more intuitive to use the Display Aspect Ratio because it just describes the final AR that the picture should take. I don't care about the pixel or sample aspect ratio, or any other convolutions that the program needs to get to the desired DAR. I just want it to get there, and using the DAR you also use the already established convetions of 4:3, 16:9 or 2.35:1, not yet another set of values to remember.
--- OFFTOPIC ---
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Old 12th July 2005, 07:25   #1144  |  Link
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At the end of the day it all comes down to the terminologies and abbreviations we give things.... We can make them as simple or as confusing as we want. And even more confusing if we use the same abbreviations to mean different things!

DAR = Display Aspect Ratio (Relates to the 2No TV/Computer monitor sizes. Which are, 4:3 and 16:9)
PAR = Pixel Aspect Ratio (Which can be any ratio you care to make)
SAR = Storage Aspect Ratio (Relates to square pixel ratio, before correction, of the movie, as it's stored in an digitized electronic form (ie: DVD, VCD, disc, disk, tape etc).
MAR = Movie Aspect Ratio (Relates to how the movie makers indend the finished production image to be viewed)

In effect SAR should not mean "Sample" it should mean "Storage"

EDIT: As Wilbert mentioned.... It comes down to "the problem is the naming of things"


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Last edited by SeeMoreDigital; 12th July 2005 at 10:02.
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Old 12th July 2005, 07:37   #1145  |  Link
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So.

Now that I found a source of the ISO/IEC 14496 Part 2:

Quote:
6.3.3 Video Object Layer
...
aspect_ratio_info: This is a four-bit integer which defines the value of pixel aspect ratio. Table 6-12 shows the meaning of the code. If aspect_ratio_info indicates extended PAR, pixel_aspect_ratio is represented by par_width and par_height. The par_width and par_height shall be relatively prime.
Code:
aspect_ratio_info  pixel aspect ratios
0000               Forbidden
0001               1:1 (Square)
0010               12:11 (625-type for 4:3 picture)
0011               10:11 (525-type for 4:3 picture)
0100               16:11 (625-type stretched for 16:9 picture)
0101               40:33 (525-type stretched for 16:9 picture)
0110-1110          Reserved
1111               extended PAR
par_width: This is an 8-bit unsigned integer which indicates the horizontal size of pixel aspect ratio. A zero value is forbidden.

par_height: This is an 8-bit unsigned integer which indicates the vertical size of pixel aspect ratio. A zero value is forbidden.
Any more questions? -- I'm afraid, yes...

And another small piece of reference to this topic:
Quote:
6.3.5.2 Video Plane with Short Header
...
source_format: This is an indication of the width and height of the rectangular video plane represented by the video_plane_with_short_header. The meaning of this field is shown in Table 6-25. Each of these source formats has the same VOP time increment resolution which is equal to 30000/1001 (approximately 29.97) Hz and the same width:height pixel aspect ratio (288/3) : (352/4), which equals 12:11 in relatively prime numbers and which defines a CIF picture as having a width:height picture aspect ratio of 4:3.
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Old 14th July 2005, 16:47   #1146  |  Link
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@yaz,

Since the MPEG-4 specs doesn't mention SAR (correct me if i'm wrong), isn't it more logical to call it PAR (or Pixel AR or whatever) instead of Sample AR?
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Old 14th July 2005, 17:19   #1147  |  Link
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The h264 / AVC specs only talk about SAR, and never mention PAR. So it's a tie.
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Old 15th July 2005, 08:51   #1148  |  Link
yaz
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Quote:
Originally Posted by Wilbert
...isn't it more logical to call it PAR (or Pixel AR or whatever) instead of Sample AR?
imho, u're right. lots of application call it par, so giving a different name just increase the confusion.
Quote:
Originally Posted by Manao
The h264 / AVC specs only talk about SAR, and never mention PAR. So it's a tie.
it can't be so hard. just see ligh's quotes. aren't they from the same specs u refer ?

however, not the name but the value(s) to be put here is(are) important. (and then call it whatever u want )

the bests
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Old 15th July 2005, 10:29   #1149  |  Link
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Quote:
Originally Posted by Manao
The h264 / AVC specs only talk about SAR, and never mention PAR. So it's a tie.
But I wonder what think their definition of think SAR means?

For all we know we might have one of those classic situations whereby the writers of one MPEG specification did not follow the meanings of the abbreviations created by the writers of former MPEG specifications.... Resulting in an confusing array of abbreviation that (of course) all look the same, but mean very different things!

For example. It's alright generating encodes at a resolution 720x576 (which I've always accepted as being the "SAR" of the encode) but whether that same encode contains any AR signalling (which I've always accepted as being "PAR" signalling) is another matter entirely!

Maybe what we need is a definitive list of all these abbreviations, with an explanation of what they mean within each MPEG specification.


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Old 22nd July 2005, 06:35   #1150  |  Link
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Question about Zones

Let me apologize if these questions about zones in x264 have been asked before. I did a forum, thread, and google search and found suspiciously little information.

I would like to know if I am mistaken in believing that x264 zones lack the ability to do "start with keyframe" as in xvid. I actually use zones twice as much for marking cut/splice points than I do for bitrate reduction.

The reason I think x264 lacks this ability is because I used the zones configuration in MeGUI, but when I went to cut the resulting mkv (using mmg/mkvmerge) I was only able to cut at -2s and +4s on either side of where I had indicated a zone boundary.

I've finally resorted to encoding the video as 5(!) separate jobs using Trim()'s in the individual avs scripts. After that I adjust fix each parts timecodes for vfr, join the parts, mux the audio, and then split it back up at the join points. This way I get good splits.

Needless to say, this really complicates things.

Can someone confirm that my experience is accurate. And if I'm not making some stupid error, I'd sure like to cast my insignificant vote for adding that feature to x264 zones.

Thanks!
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Old 22nd July 2005, 07:41   #1151  |  Link
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I remember that this has come up before. But your scenario is so special that I wouldn't count on anything happening.
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Old 27th July 2005, 07:29   #1152  |  Link
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Thanks!

I just finished editing Noir ep. 1 (35089 frames processed by hand in 14 days of work). I am now encoding the final output using the newest x264 (v. 280). The file is ridiculously small (at q=20); I'm using ESA motion estimation and all the highest quality settings possible. Here is the commandline:

x264.exe --progress --qp 20 --subme 6 --ref 1 --threads 1 --filter 0:0 --keyint 250 --min-keyint 25 --scenecut 40 --qpmin 10 --qpmax 51 --qpstep 4 --direct temporal --me esa --merange 16 --bframes 15 --weightb --b-bias 0 --ipratio 1.40 --pbratio 1.30 --qcomp 0.60 --analyse all --8x8dct --progress --fps 23.97600000 --sar 32:27 -o "F:\Video Files\Noir\Encoded\Noir.01.mp4" "F:\AVISynth Scripts\Noir\MP4 Output\Noir.01.avs"

I am very impressed with the quality this codec is achieving; it could only be excelled by Ateme among all other codecs in the world right now. My AthlonXP 2500+ running single-channel DDR400 gets about 3.2-3.5 fps (no filters in the avs):

avisource("F:\Video Files\Noir\Frameserved from Vegas\Noir.01.avi")
killaudio()
converttoyv12()

The avisource() line should explain why I used killaudio()! This unusual setup is due to the fact that Vegas 6.0 starts sending corrupt frames to saved AVI files after about f4000.

So many thanks to the developers; in combination with my intensively laborious hand-editing (or rather, choosing for replacement) of video frames, the codec is a perfect match for my insistence on perfect output, in archival grade.

Tomorrow or Thursday I will be posting the link to my new site, which will explain the techniques used in this process. Particularly, delta codecs such as x264 can benefit enormously from having source frames that differ only in quantization and film-grain noise replaced by the best among a group. This zeroes whole groups of frames - sometimes quite substantial in size.

Due to the high quality of x264, it tends to preserve noise much better than MPEG-4 ASP codecs, due to more efficient bit allocation at equivalent bitrates. Thus at equivalent bitrates, the value of source noise reduction is increased by a substantial amount. Beyond the saving of bits, choosing superior frames for replicative replacement of inferior ones increases the psychovisual quality of a video stream and is a powerful tool to provide a 'free' quality boost. It is time-intensive, though; The curent project is estimated to take one year and one month to complete.

Since encoding time is less than 5% of the time to produce a finished release, I'm not concerned about slow encoding speeds. Since I've invested so much time in the other 95%+, I use the most perfect encoding settings I know of.

If anyone knows of any way to make x264 run slower but achieve higher quality, please do point out the parameters that should be changed in the commandline above. Acceptable framerate for encoding is 0.1 FPS. Thanks!

Last edited by Isochroma; 27th July 2005 at 07:35.
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Old 27th July 2005, 09:41   #1153  |  Link
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Quote:
Originally Posted by Isochroma
If anyone knows of any way to make x264 run slower but achieve higher quality, please do point out the parameters that should be changed in the commandline above. Acceptable framerate for encoding is 0.1 FPS. Thanks!
How about 2- or 3-pass encoding, --ref 15, --b-pyramid and --keyint 500 (this should be tested; probably no gain and may lose seeking precision).

Last edited by nm; 27th July 2005 at 09:47.
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Old 27th July 2005, 13:06   #1154  |  Link
LigH
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Instead of
Code:
avisource("F:\Video Files\Noir\Frameserved from Vegas\Noir.01.avi")
killaudio()
converttoyv12()
simply try
Code:
avisource("F:\Video Files\Noir\Frameserved from Vegas\Noir.01.avi", false, "YV12")
This shall speed up a little, because it does not "request and delete" unnecessary data, but instead requests only desired.
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Old 27th July 2005, 15:56   #1155  |  Link
akupenguin
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Quote:
Originally Posted by nm
--keyint 500 (this should be tested; probably no gain and may lose seeking precision)
--keyint is just a maximum. If increasing it removes some I-frames, then you both lose seeking precision and gain compression. If not, nothing changes.
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Old 29th July 2005, 01:48   #1156  |  Link
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right,
sorry to be the pestering noob but...

"x264 options explained, step by step guide"

where?
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Old 29th July 2005, 06:52   #1157  |  Link
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Quote:
Originally Posted by posix
right,
sorry to be the pestering noob but...

"x264 options explained, step by step guide"

where?


also what does this have to do with x264 development?

striked
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Old 29th July 2005, 11:02   #1158  |  Link
LigH
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@ posix:

Because you seem to be a German, you may want to look in the german doom9/Gleitz board for Selur's "Wissenswertes rund um x264".

http://forum.gleitz.info
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Old 4th August 2005, 20:49   #1159  |  Link
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Where to actually report possible bugs in x264?

This one is assertion exception, raised apparently in x264 whilst encoding with VirtualDub.

http://forums.virtualdub.org/index.p...&f=15&t=10297&
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Old 13th August 2005, 14:17   #1160  |  Link
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x264.exe does not yet have a special "encode interlaced" option, as far as I can see in the help output of rev. 284 - or did I miss an option?
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