[FFmpeg-user] Meaning of ffprobe output

Ulf Zibis Ulf.Zibis at gmx.de
Sat Feb 2 21:32:25 EET 2019

Am 02.02.19 um 19:27 schrieb Ulf Zibis:
> But if I have a interlaced encoded stream with interlaced content, I
> guess only both steps at same time ensure to get a progressive stream
> with good visual quality.

For this case I see 2 options. Assume we have a 25 fps top first
interlaced encoded stream with interlaced content:

1. Use one of the plenty given de-interlace filters, remove the
interlaced flag and result in a 25 fps progressive stream.

2. Duplicate each frame and in the duplicate replace the top field with
the top field of the succeeding frame, remove the interlaced flag and
result in a 50 fps progressive stream, where only half of the lines are
changed from frame to frame.

The 1st method more or less suffers from the known de-interlacing
artefacts. The 2nd would fully keep the advantages of the old CRT
display method.

The 2nd method doubles the bit rate of the raw stream, but I believe,
when it comes to compression, the encoder could profit from the
successive lines with same content, so the encoded result may have the
same bit rate by equal quality for both ("de-interlace") methods.

The 2nd method is, what a software player could do with a valid 
interlaced encoded stream with interlaced content and then feed the
display controller with such a 50 fps stream for the presentation on a
progressive LCD/LED display.

Is that too sophisticated rocket science?


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