[FFmpeg-user] Meaning of ffprobe output

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Jan 30 22:23:46 EET 2019

2019-01-30 18:27 GMT+01:00, Carl Zwanzig <cpz at tuunq.com>:
> On 1/30/2019 6:12 AM, Carl Eugen Hoyos wrote:
>> You may have forgotten that while the vertical resolution is kept,
>> horizontal resolution is reduced significantly for VHS, likely
>> confusing the algorithm for detection of interlaced content.
> Exactly, VHS only has bandwidth of ~3MHz, so a horizontal
> resolution of ~240 TV lines (not pixels). There can also be
> a -lot- of variable horizontal smearing (plus other artifacts).

> AFAIK all VHS players produce an interlaced signal

Of course (and what you write is correct to the best of
my knowledge) but please note that - at least as far as
I am concerned - this is not about the "signal" that is of
course interlaced for analog PAL but the content that
may of may not be interlaced (and the idet filter only
looks at the content and nothing in FFmpeg is able to
look at an analog video signal).

Carl Eugen

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