Ok, for the second alternative (using TEE.BAT) I managed to output something.
I had to add > before the log filename, and also remove the @ before the command in the bat file.
But, all I get in the log is the question, my input command:
D:\Programas\VIDEO\x264-2245.exe --level 4.1 --preset slower --tune film --pass 1 --bitrate 1500 --deblock -2:-1 --keyint 300 --min-keyint 30 --aq-strength 1.2 --fps 29.970 --output NUL Copia.avs
and not my answer (or Q&A together):
C:\OEM>D:\Programas\VIDEO\x264-2245.exe --level 4.1 --preset slower --tune film --pass 1 --bitrate 1500 --deblock -2:-1 --keyint 300 --min-keyint 30 --aq-strength 1.2 --fps 29.970 --output NUL Copia.avs
avs [info]: 720x480p 0:0 @ 30000/1001 fps (cfr)
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
x264 [info]: profile Main, level 4.1
[1.0%] 1/101 frames, 1.10 fps, 2075.60 kb/s, eta 0:01:30
[14.9%] 15/101 frames, 12.98 fps, 1109.24 kb/s, eta 0:00:06
[34.7%] 35/101 frames, 24.89 fps, 1600.93 kb/s, eta 0:00:02
[74.3%] 75/101 frames, 45.29 fps, 1476.59 kb/s, eta 0:00:00
x264 [info]: frame I:1 Avg QP:21.54 size: 8657
x264 [info]: frame P:29 Avg QP:18.16 size: 9658
x264 [info]: frame B:71 Avg QP:18.83 size: 4739
x264 [info]: consecutive B-frames: 2.0% 2.0% 32.7% 63.4%
x264 [info]: mb I I16..4: 87.7% 0.0% 12.3%
x264 [info]: mb P I16..4: 59.9% 0.0% 0.0% P16..4: 32.6% 0.0% 0.0% 0.0% 0.0% skip: 7.6%
x264 [info]: mb B I16..4: 18.1% 0.0% 0.0% B16..8: 31.6% 0.0% 0.0% direct:29.6% skip:20.7% L0:42.6% L1:43.7% BI:13.7%
x264 [info]: final ratefactor: 18.81
x264 [info]: direct mvs spatial:97.2% temporal:2.8%
x264 [info]: coded y,uvDC,uvAC intra: 45.7% 62.9% 8.7% inter: 19.3% 46.7% 0.5%
x264 [info]: i16 v,h,dc,p: 37% 28% 28% 7%
x264 [info]: i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 23% 24% 7% 6% 4% 8% 5% 12%
x264 [info]: i8c dc,h,v,p: 53% 23% 23% 2%
x264 [info]: Weighted P-Frames: Y:0.0% UV:0.0%
x264 [info]: kb/s:1484.21
encoded 101 frames, 56.20 fps, 1484.21 kb/s