.avi interlace or progressive flag

[marcorocchini]

Hi, please can you help a c*t?

I have 2 video .avi files:

one is an uncompressed interlaced video file https://dl.dropboxusercontent.com/u/39871584/INTERLACE.AVI

and one is uncompressed progressive video file https://dl.dropboxusercontent.com/u/39871584/PROGRESSIVE.AVI

MediaInfo correctly recognize the interlaced one as interlaced, and the progressive one as progressive.

But now I wonder: using the HEX editor, can I modify a flag of the progressive one so that it is recognized as interlaced?

Thanks

[jagabo]

See the ODML extensions, the vprp chunk.

http://abcavi.kibi.ru/docs/odml1.pdf

Example analysis from your interlaced file:

76 70 72 70 header fourcc          "vprp"
64 00 00 00 size                   100 bytes

00 00 00 00 VideoFormatToken       0=UNKNOW
01 00 00 00 VideoStandard          1=STANDARD_PAL
32 00 00 00 dwVerticalRefreshRate  50
80 07 00 00 dwHTotalInT            1920
38 04 00 00 dwVTotalInLines        1080
03 00 04 00 dwFrameAspectRatio     3:4 ???
80 07 00 00 dwFrameWidthInPixels   1920
38 04 00 00 dwFrameHeightInLines   1080
02 00 00 00 nbFieldPerFrame        2

FieldInfo[0]
20 02 00 00 CompressedBMHeight     544
80 07 00 00 CompressedBMWidth      1920
1c 02 00 00 ValidBMHeight          540
80 07 00 00 ValidBMWidth           1920
00 00 00 00 ValidBMXOffset         0
00 00 00 00 ValidBMYOffset         0
7a 00 00 00 VideoXOffsetInT        122
18 00 00 00 VideoYValidStartLine   24

FieldInfo[1]
20 02 00 00 CompressedBMHeight     544
80 07 00 00 CompressedBMWidth      1920
1c 02 00 00 ValidBMHeight          540
80 07 00 00 ValidBMWidth           1920
00 00 00 00 ValidBMXOffset         0
00 00 00 00 ValidBMYOffset         0
7a 00 00 00 VideoXOffsetInT        122
50 01 00 00 VideoYValidStartLine   336

You can make MediaInfo report the progressive video as interlaced simply by changing the nbFieldPerFrame from 1 to 2. But that doesn't make the video interlaced and the video data will be laid out wrong (not over/under format). Any program that really uses the vprop information will get confused. To do it properly you'll need to change other values in the vprp header and separate the fields within the video chunks.

[marcorocchini]

76 70 72 70 header fourcc          "vprp"
64 00 00 00 size                   100 bytes

00 00 00 00 VideoFormatToken       0=UNKNOW
01 00 00 00 VideoStandard          1=STANDARD_PAL
32 00 00 00 dwVerticalRefreshRate  50
80 07 00 00 dwHTotalInT            1920
38 04 00 00 dwVTotalInLines        1080
03 00 04 00 dwFrameAspectRatio     3:4 ???
80 07 00 00 dwFrameWidthInPixels   1920
38 04 00 00 dwFrameHeightInLines   1080
02 00 00 00 nbFieldPerFrame        2

FieldInfo[0]
20 02 00 00 CompressedBMHeight     544
80 07 00 00 CompressedBMWidth      1920
1c 02 00 00 ValidBMHeight          540
80 07 00 00 ValidBMWidth           1920
00 00 00 00 ValidBMXOffset         0
00 00 00 00 ValidBMYOffset         0
7a 00 00 00 VideoXOffsetInT        122
18 00 00 00 VideoYValidStartLine   24

FieldInfo[1]
20 02 00 00 CompressedBMHeight     544
80 07 00 00 CompressedBMWidth      1920
1c 02 00 00 ValidBMHeight          540
80 07 00 00 ValidBMWidth           1920
00 00 00 00 ValidBMXOffset         0
00 00 00 00 ValidBMYOffset         0
7a 00 00 00 VideoXOffsetInT        122
50 01 00 00 VideoYValidStartLine   336

please jagabo wich program are you using to achieve this informations?

[jagabo]

I did a simple hex dump and made the notes myself in Notepad.

[marcorocchini]

but I need to understand:

for example the string "544" is traduced is 20 02 00 00 ?
the string "1920" is "80 07 00 00" ?

but for example 80 07 00 00 is a hexadecimal value?

and for example 720 and 576 what correspond to?

[jagabo]

the string "1920" is "80 07 00 00" ?

Intel processors are little endian. So you need to reverse the order of the bytes. 80 07 00 00 --> 00 00 07 80 --> 00000780 --> 780. Use a hex calculator to convert from hex to decimal. Windows' built in calculator has a Programmer mode that has hex/decimal conversion. 780 hex is 1920 decimal.

[marcorocchini]

03 00 04 00 dwFrameAspectRatio     3:4 ???

please jagabo I would set this aspect ratio to 16:9 (par 16:9?) in this case what is the values correct to put in place of 03 00 04 00?

[jagabo]

Use a hex calculator or table.

dec hex
--- ---
 0   0
 1   1
 2   2
 3   3
 4   4
 5   5
 6   6
 7   7
 8   8
 9   9
10   A
11   B
12   C
13   D
14   E
15   F

[marcorocchini]

[Attachment 40893 - Click to enlarge]


please help a cat

[jagabo]

Why don't you just read the documentation, experiment, and figure it out for yourself. Here's a hint:

word = 2 byte value
dword = 4 byte value

Since AVI is a native Microsoft format, Microsoft has usually used Intel processors, and Intel processors are always little endian, multibyte values are stored least significant byte first, most significant byte last. So the two byte (word) hex value 1234 is stored in memory as 34 12. The four byte (dword) hex value 12345678 is stored in memory as 78 56 34 12.

http://www.ascii.cl/conversion.htm

[marcorocchini]

oh my cat

[marcorocchini]

my pow cannot press key in the numpad

[marcorocchini]

please help a c**

[jagabo]

Just put in different numbers and see how it effect playback of the video.

[marcorocchini]

* my paw

[jagabo]

Then even if I give you the numbers you won't be able to type them in.

[marcorocchini]

mmm but I'm able with mouse and copy and paste

[jagabo]

Then copy and paste from the hex chart I linked to.

[marcorocchini]

Jagabo please help me: considerting this mjpeg interlace video file:
https://dl.dropboxusercontent.com/u/39871584/mjpegInterlace.avi


And this mjpeg progressive video file:
https://dl.dropboxusercontent.com/u/39871584/mjpegProgressive.avi

can you tell me where is the flags internally the files that tell to mediainfo that they are interlaced/progressive?

this mjpeg .avi don't have the vprp section

thanks

[jagabo]

It's in Mainconcept's private AVI1 chunk, the first byte is a 01 instead of 00. Each frame has an AVI1 chunk. Changing the first one (at address FE12) will cause MediaInfo to report the video as interlaced. But it may not be decoded properly, depending on what MJPG decoder is used (ffmpeg and lsmash return a picture that looks ok, PicVideo's MJPEG decoder doesn't). And, of course, even if the decoder decompresses the video, it will not be interlaced.

[marcorocchini]

Ah interesting, Jagabo please help me cat:

this time consider this small avi from FFMPEG in mjpeg:
https://dl.dropboxusercontent.com/u/39871584/mjpegFFmpeg.avi

mediainfo see it as progressive, is there a way to "force" it to see as interlaced?

[jagabo]

That has a vprp chunk but it only has one FieldInfo structure in that chunk. Changing the nbFieldPerFrame value to 2 doesn't cause MediaInfo to report it as interlaced -- though it doesn't report progressive either. Presumably because there is now a discrepancy between the the nbFieldPerFrame value and the number of FieldInfo structures.