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Setting B frames in a video using ffmpeg

According to the ffmpeg manual, the installation -gconsists of defining a space between frames “I” and setting -bfto use frames “B”. The first thing I got, but the last not.

Purpose: I am trying to get a video with GOP 3.12 (M = 3, N = 12). This means: 2 frames of "B" separating each "P" frame, and "I" frames with 12 frames of distance. Or simply: "IBBPBBPBBPBBI"

I think I only got N = 12 using the following commands:

  • ffmpeg -s cif -r 30 -b 64000 -bt 3200 -g 12 -y -i video.yuv -vcodec mpeg4 video.m4v
  • MP4Box -hint -mtu 1460 -fps 30 -add video.m4v video.mp4
  • ffmpeg -y -i video.mp4 video_ref.yuv
  • ../cmd/psnr 352 288 420 video.yuv video_ref.yuv > psnr_ref.txt
  • ../cmd/mp4trace -f -s 192.168.0.2 12346 video.mp4 > trace
  • head -n 20 trace

Result:

[robert@10-2Fontes]$ head -n 20 trace
1   H   12002   9   0.000
2   P   11479   8   0.034
3   P   12021   9   0.066
4   P   11239   8   0.099
5   P   5407    4   0.134
6   P   2735    2   0.166
7   P   1014    1   0.199
8   P   850 1   0.232
9   P   619 1   0.265
10  P   979 1   0.298
11  P   813 1   0.331
12  P   806 1   0.364
13  H   5109    4   0.396

* , -g 12 ffmpeg, . , , - "", cif: http://www2.tkn.tu-berlin.de/research/evalvid/cif.html

, "H" "I" .

-bf 2 ffmpeg, (, "B" )

ffmpeg -s cif -r 30 -b 64000 -bt 3200 -g 12 -bf 2 -y -i video.yuv -vcodec mpeg4 video.m4v

:

[robert@10-2Fontes]$ head -n 20 trace
1   H   12002   9   0.001
2   P   11479   8   0.034
3   P   12021   9   0.067
4   P   11239   8   0.100
5   P   5407    4   0.132
6   P   2735    2   0.166
7   P   1014    1   0.199
8   P   850 1   0.232
9   P   619 1   0.265
10  P   979 1   0.298
11  P   813 1   0.331
12  P   806 1   0.363
13  H   5109    4   0.400
+5
1

:

, ffmpeg.

: ffmpeg [ ] [ ] -i [ ] -

( -g 30 -bf 2), :

ffmpeg -s cif -r 30 -i video.yuv -vcodec mpeg4 -g 30 -bf 2 video.m4v

. . , "". , , sth , ( ), .

:

[robert @10-2Fontes] $head -n 40 trace

1 H 12038 9 0.034

2 P 13204 10 0,132

3 B 5367 4 0,132

4 B 5553 4 0,132

5 P 12157 9 0,232

6 B 5069 4 0,322

7 B 5613 4 0,322

8 P 12739 9 0,334

9 B 5935 5 0,344

10 B 3921 3 0,334

11 P 4474 4 0,429

12 B 1247 1 0.429

13 B 784 1 0.429

14 P 1448 1 0,528

15 B 350 1 0,528

16 B 397 1 0,528

17 P 1023 1 0,627

18 B 299 1 0,633

19 B 265 1 0,634

20 P 829 1 0,727

21 B 209 1 0.733

22 B 340 1 0.733

23 P 867 1 0,826

24 B 343 1 0,833

25 B 378 1 0,833

26 P 865 1 0,925

27 B 282 1 0,925

28 B 461 1 0,925

29 H 5083 4 1.034

30 B 818 1 1.034

31 B 838 1 1.034

32 P 1171 1 1.122

33 B 443 1 1.133

34 B 409 1 1.133

35 P 1078 1 1.221

36 B 269 1 1.233

37 B 327 1 1.233

38 P 795 1 1.321

39 B 298 1 1.333

40 B 304 1 1,334

41 P 854 1 1.419

42 B 477 1 1.419

43 B 412 1 1.419

44 P 869 1 1,519

45 B 371 1 1,519

46 B 314 1 1,519

47 P 983 1 1,617

48 B 337 1 1,617

49 B 454 1 1.617

50 P 1118 1 1.717

51 B 286 1 1.717

52 B 275 1 1.717

53 P 1044 1 1,815

54 B 362 1 1,815

55 B 273 1 1,815

56 P 973 1 1,914

57 B 302 1 1,914

58 B 324 1 1,915

59 H 4525 4 2,033

+2

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