CODEWITHSUNDEEP
videocompressionvideo-streamingh.264
user3335040
user3335040

Reputation: 669

In H264, what does the field_pic_flag mean and does it have a relation to encoding intervals?

I am looking at a H264 stream which has all true field_pic_flags in every slice header. The standard says the following about it:

field_pic_flag equal to 1 specifies that the slice is a slice of a coded field. field_pic_flag equal to 0 specifies that the slice is a slice of a coded frame. When field_pic_flag is not present it shall be inferred to be equal to 0.

Can anybody elaborate on what a field_pic_flag signifies, what the difference between a field / frame is, and what the significance of having all field_pic_flags = 1 is?

The video also has a set Encoding Interval / Gov Length: 1 iframe 69 pframes 1 iframe 69 pframes 1 iframe 69 pframes etc etc.... Does the field_pic_flag have any relation to this interval?

Upvotes: 3

Views: 1653

Answers (1)

nobody555
nobody555

Reputation: 2374

It means exactly what is written in spec i.e. specify if is full frame or field. As for difference between frame and field you should read about interlaced video and field (video). In short field is half vertical resolution part (only odd or even lines) of full frame. And no field_pic_flag doesn't have anything todo with "intervals". For the note field_pic_flag=1 is only used for encoding interlaced video with PAFF coding (there is also MBAFF coding for interlaced video).

Upvotes: 3

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