720x480播放时变848是如何实现的- -

Video
ID                               : 1
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : Main@L3.0
Format settings, CABAC           : Yes
Format settings, ReFrames        : 3 frames
Codec ID                         : avc1
Codec ID/Info                    : Advanced Video Coding
Duration                         : 23mn 41s
Bit rate mode                    : Variable
Bit rate                         : 430 Kbps
Maximum bit rate                 : 4 945 Kbps
Width                            : 720 pixels
Height                           : 480 pixels
Display aspect ratio             : 16:9
Original display aspect ratio    : 16:9
Frame rate mode                  : Constant
Frame rate                       : 23.976 fps
Standard                         : NTSC
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.052
Stream size                      : 72.9 MiB (81%)
Writing library                  : x264 core 114 r1913 5fd3dce
Encoding settings                : cabac=1 / ref=3 / deblock=1:-1:-1 / analyse=0x1:0x111 / me=tesa / subme=10 / psy=1 / psy_rd=0.00:0.00 / mixed_ref=1 / me_range=32 / chroma_me=1 / trellis=2 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=0 / threads=24 / sliced_threads=0 / nr=0 / decimate=0 / interlaced=0 / constrained_intra=0 / bframes=3 / b_pyramid=0 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=240 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=85 / rc=crf / mbtree=1 / crf=19.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / vbv_maxrate=10000 / vbv_bufsize=10000 / crf_max=0.0 / nal_hrd=none / ip_ratio=1.40 / aq=2:0.80