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我想3GP電影轉換爲H264視頻(MP4) 這是我在用的:這個ffmpeg命令有什麼問題?
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"
的問題是原始文件是28KB,但轉換後,我得到155KB MP4文件 爲什麼文件如此臃腫 - 是因爲尺寸還是其他選項?
以下是我對3GP輸入文件中看到:注意比特率是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
這是我看到的MP4輸出文件:注意比特率是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
有你嘗試設置視頻比特率和最大比特在沒有任何價值的情況下,編碼器應該使用默認值,並且可以解釋視頻軌道增長如此之多。 – alexbuisson