According to ffmpeg manual, setting -g is to define space between "I" frames, and setting -bf to use "B" frames. The former I got, but the latter not.
The goal: I'm trying to have a video with a GOP 3,12 (M= 3, N=12). That means: 2 "B" frames separating each "P" frames, and "I" frames with 12 frames of distance. Or simply: "IBBPBBPBBPBBI"
I think that I got only the N=12, using the commands below:
ffmpeg -s cif -r 30 -b 64000 -bt 3200 -g 12 -y -i video.yuv -vcodec mpeg4 video.m4vMP4Box -hint -mtu 1460 -fps 30 -add video.m4v video.mp4ffmpeg -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 > tracehead -n 20 traceResult:
[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
*Note, the most important is the command -g 12 in ffmpeg, but I writing all the commands. The video that I'm using is the "highway", from cif page videos: http://www2.tkn.tu-berlin.de/research/evalvid/cif.html
I don't know why the result trace is using "H" instead of "I".
I tried to put -bf 2 in ffmpeg command, but did not worked (I think because I saw no "B" indications in the result)
List item
ffmpeg -s cif -r 30 -b 64000 -bt 3200 -g 12 -bf 2 -y -i video.yuv -vcodec mpeg4 video.m4v
Result:
[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
Solved:
Like LordNeckbeard said, option placement matters in ffmpeg.
Basic order is:
ffmpeg [global options] [input options] -i input [output options] output
I changed to the command below (putting -g 30 -bf 2) and it works:
ffmpeg -s cif -r 30 -i video.yuv -vcodec mpeg4 -g 30 -bf 2 video.m4v
Note: Even after changed in the first time did not worked. The program asked me to overwrite the files and I said Yes. But apparently sth was not removed, at the moment I removed all files and did it again (from zero) it worked.
Now the result is:
[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 0.232
7 B 5613 4 0.232
8 P 12739 9 0.334
9 B 5935 5 0.334
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