.AVI header: where is the flag that tell to the decompress if interlaced?

[marcorocchini]

Hi, please can anyone help a Cat??

please consider this 2 uncompressed video files:

this is recognized from my NLE as progressive:
https://www.dropbox.com/s/00dnango1nwn8h0/progressive.AVI?dl=0


and this as interlaced:
https://www.dropbox.com/s/06vvc4n5asr1iw9/interlaced.AVI?dl=0


I wonder: in the .avi header where is locate exactly the flag that tell to the decoder if the videofile is interlaced or progressive. What is the hex values that signal if the video is interlaced or progressive?

[Vidd]

The AVI container does not have a flag or header information that indicates interlace or progressive. If the codec used in the AVI container supports interlace it would have to specified somewhere, usually in the bitstream or in the codec-specific data area "strd" chunk.

Your screenshot shows the MJPEG codec. A MJPEG encoded video stores 2 images per frame for interlace and 1 image per frame for progressive. The NLE probably analyzes the bitstream and detects the 2 images per frame and displays it as interlace.

[marcorocchini]

oh sorry cat, I have export in mjpeg instead of uncompress, however now I have correct the post

please can you tell me if there exist a program that analyze the avi header of this files?

progressive





interlaced

[_Al_]

You need to get that info with batch script, using mediainfo ... we discussed it before, then store it and apply appropriate avisynth line (or whatever you need). Then you switched to ffprobe, not sure how to get it there, I think I had problem to determine top or bottom field first there. MediaInfo privides that. You got script as well.

So yet again it was discussed already together with scripts, and we are back at the begging

To determine top or bottom in the video, after you loose that info or for whatever reason: http://avisynth.nl/index.php/Interlace_detection
But it is kind of insane in your case, because you can have that info from original. We are not talking about unknown source. Your source is known and then you loose that info. ... You might even store that info into that uncompressed avi filename, not hacking hex values (using mediainfo and batch or whatever you use to get that uncompressed).

[DB83]

Maybe I am having a senior moment but I thought that, generally, uncompressed video is always 'progressive'. Or to put it another way each frame is complete and contains all the information.

I wasted some time downloading those samples and the one called 'progressive' is not as such.

[_Al_]

download mediainfo cli, not gui from Videohelp, direct link here, then use this to store field order into avi name, it is going to add suffix: _none, _bff or _tff into filename

SET Mediainfo="C:tools\Mediainfo CLI\Mediainfo.exe"
call :run_mediainfo "%aviname%"
for %%i in ("%aviname%") do set "aviname=%%~dpni_%field_order%%%~xi"
.
.


:run_mediainfo
%mediainfo% "%~1" > "mediainfo.txt"
findstr /c:"Scan order                               : Bottom Field First"  "mediainfo.txt" >nul
  if %errorlevel%==0 SET field_order=bff& set scan_order=Bottom Field First
findstr /c:"Scan order                               : Top Field First"     "mediainfo.txt" >nul
  if %errorlevel%==0 SET field_order=tff& set scan_order=Top Field First
findstr /c:"Scan type                                : Progressive"         "mediainfo.txt" >nul
  if %errorlevel%==0 SET field_order=none& SET scan_type=progressive
findstr /c:"Scan type                                : Interlaced"          "mediainfo.txt" >nul
  if %errorlevel%==0 SET scan_type=interlaced
goto :eof

then use this code to read that info:

for %%i in ("%aviname%") do set "just_name=%%~ni"
for /f "tokens=2 delims=_" %%i in ("%just_name%") do  set "field_order=%%i"
rem field_order is none or tff or bff

so for whatever reason, you loose the track what that uncompressed is, you have that info written into filename itself