Question

我的目标是压缩视频以使其比特率更低。对于实验，我使用了以下命令

ffmpeg -ss 00:00:00 -i V.mkv -to 00:10:00 -c:a copy -b:v 7500k -maxrate 7500k -minrate 5500k -bufsize 1M V7500.mkv

1。使用全部8个内核的转换速度接近1.0倍的可能原因是什么？
2.输出视频流的比特率约为4700（将5500设置为分钟率）。有指定比特率的正确方法吗？

Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[libx264 @ 0x55e54ad189a0] using SAR=1/1
[libx264 @ 0x55e54ad189a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x55e54ad189a0] profile High, level 4.0
[libx264 @ 0x55e54ad189a0] 264 - core 152 r2854 e9a5903 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=23 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=cbr mbtree=1 bitrate=7500 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=7500 vbv_bufsize=1000 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'V7500.mkv':
  Metadata:
    title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
    encoder         : Lavf57.83.100
    Chapter #0:0: start 0.000000, end 600.000000
    Metadata:
      title           : Chapter 01
    Stream #0:0(eng): Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 1920x804 [SAR 1:1 DAR 160:67], q=-1--1, 7500 kb/s, 23.98 fps, 1k tbn, 23.98 tbc (default)
    Metadata:
      title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
      DURATION        : 02:17:03.277000000
      encoder         : Lavc57.107.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 7500000/0/7500000 buffer size: 1000000 vbv_delay: -1
    Stream #0:1(eng): Audio: aac (LC) ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, fltp (default)
    Metadata:
      title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
      ENCODER         : Lavc57.107.100 aac
      DURATION        : 02:17:03.317000000
Past duration 0.994987 too large
frame=14385 fps= 31 q=-1.0 Lsize=  363641kB time=00:09:59.99 bitrate=4964.9kbits/s speed=1.28x

ffmpeg低速和错误的比特率

0 个答案: