Dropped frames after encoding (30fps -> 20fps)?

[SaiQmon]

Hi!

I've captured few videos with my ACT35 bullet cam and it's supposed to be 1080P 30fps material. It takes about 100Mbs / minute, MP4 file with native H264 (by specifications).

When I open it with VLC player, everything is ok:

Codec: H264 - MPEG-4 AVC (part 10) (avc1)
Resolution: 1920x1080
Frame rate: 30
Decoded format: Planar 4:2:0 YUV
Codec: MPEG AAC Audio (mp4a)
Channels: Stereo
Sample rate: 48000 Hz

I've also checked it manually with virtualdub, there really is 30 different frames per second.

But when I edit it with VideoPad (from NCH Software) and export it with:

Resolution: 1920x1080
Frame rate: 30
Encoder: H264 AVI
Quality: 15 (from 1 to 50 scale)

I get 30fps file, but some frames are duplicated and there are only 20 different frames per second. (calculated manually on VirtualDub preview). The difference is significant, encoded video doesn't run very "smoothly".

- Every 3rd frame is a duplicate

I've tried also MPEG encoding, no help.

* *

I also found, that if I use 60fps original material and encode it to 30fps, it really is 30fps different frames...

Why is this? Is it something with VideoPad or is this a common issue with H264 or so?

- BR, Simo

[SaiQmon]

Replying myself..

I've located the problem to overlay image with chroma key.

- With overlay = 25 different frames per second
- Wihout overlay = 30 different frames per second

Seems to be VideoPad issue?