Just to make sure you get me right:
Slicing original video file than joining slices back produce smaller output file than original input.
Joining same slices of original video again and again each time produces output files with different size, but equal size on disk.
After that slicing already rejoined video and joining it back again and again each time produce output files with same size as expected.
I have multiple files I want to slice, and slicing & joining any of them give same improper result.
Here's the link to the smallest one (though it's 5Gb):
https://onedrive.live.com/redir?resid=501FA25B75FA2E06!75047&authkey=!AE-j8qsLrOVYDsI&ithint=video%2caviFile properties by MediaInfo:
Format: AVI
Format/Info: Audio Video Interleave
Commercial name: DVCPRO
Format profile: OpenDML
File size: 4.94 GiB
Duration: 23mn 9s
Overall bit rate mode: Constant
Overall bit rate: 30.5 Mbps
Video
ID: 0
Format: DV
Commercial name: DVCPRO
Codec ID: dvsd
Codec ID/Hint: Sony
Duration: 23mn 9s
Bit rate mode: Constant
Bit rate: 24.4 Mbps
Encoded bit rate: 28.8 Mbps
Width: 720 pixels
Height: 576 pixels
Display aspect ratio: 4:3
Frame rate mode: Constant
Frame rate: 25.000 fps
Standard: PAL
Color space: YUV
Chroma subsampling: 4:2:0
Bit depth: 8 bits
Scan type: Interlaced
Scan order: Bottom Field First
Compression mode: Lossy
Bits/(Pixel*Frame): 2.357
Stream size: 4.66 GiB (94%)
Audio
ID: 1
Format: PCM
Format settings, Endianness: Little
Format settings, Sign: Signed
Codec ID: 1
Duration: 23mn 9s
Bit rate mode: Constant
Bit rate: 1 536 Kbps
Channel(s): 2 channels
Sampling rate: 48.0 KHz
Bit depth: 16 bits
Stream size: 254 MiB (5%)
Alignment: Aligned on interleaves
Interleave, duration: 10 ms (0.25 video frame)
Interleave, preload duration: 2990 ms