ffmpeg - 这个 ffmpeg 命令有什么问题？

Question

我正在尝试将 3gp 电影转换为 H264 视频 (mp4)
这就是我正在使用的:

ffmpeg -i file8.3gp -vcodec libx264 -preset slow -vf scale="720:trunc(ow/a/2)*2" -threads 0 -acodec libvo_aacenc -b:a 128k "file8.mp4"

问题是原始文件是 28kb 但转换后我得到 155kb mp4 文件
为什么文件如此臃肿 - 是因为大小还是其他选项？

这是我在 3gp 输入文件上看到的内容:注意比特率为 46 KB/S

libavutil      52. 39.100 / 52. 39.100
  libavcodec     55. 18.102 / 55. 18.102
  libavformat    55. 12.102 / 55. 12.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 80.101 /  3. 80.101
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file8.3gp':
  Metadata:
    major_brand     : 3gp5
    minor_version   : 256
    compatible_brands: 3gp53gp4
    creation_time   : 2005-10-28 17:36:40
  Duration: 00:00:04.93, start: 0.000000, bitrate: 46 kb/s
    Stream #0:0(eng): Audio: amr_nb (samr / 0x726D6173), 8000 Hz, mono, flt, 8 k
b/s
    Metadata:
      creation_time   : 2005-10-28 17:36:40
      handler_name    : Apple Sound Media Handler
    Stream #0:1(eng): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p
, 176x144 [SAR 1:1 DAR 11:9], 35 kb/s, 15 fps, 15 tbr, 600 tbn, 1k tbc
    Metadata:
      creation_time   : 2005-10-28 17:36:40
      handler_name    : Apple Video Media Handler

这是我在 mp4 输出文件中看到的内容:注意比特率为 243 KB/S

libavutil      52. 39.100 / 52. 39.100
  libavcodec     55. 18.102 / 55. 18.102
  libavformat    55. 12.102 / 55. 12.102
  libavdevice    55.  3.100 / 55.  3.100
  libavfilter     3. 80.101 /  3. 80.101
  libswscale      2.  3.100 /  2.  3.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file8.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.12.102
  Duration: 00:00:05.20, start: 0.200000, bitrate: 243 kb/s
    Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 720x588 [
SAR 539:540 DAR 11:9], 240 kb/s, 15 fps, 15 tbr, 15360 tbn, 30 tbc
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 8000 Hz, mono, fltp, 10 kb
/s
    Metadata:
      handler_name    : SoundHandler
At least one output file must be specified

Answer 1

试试 -vf "scale=720:trunc(ow/a/2)*2"
祝你今天过得愉快 ;)