1.
AVAssetExportPresetMediumQuality和
AVAssetExportPreset960x540 码率相差很大，视频大小也会相差很大
AVAssetExportPresetMediumQuality
empdeMac-mini:OPS temp$ ffmpeg -i /Users/temp/Library/Developer/CoreSimulator/Devices/51C23BB1-86A1-4787-90DD-81D855E2A372/data/Containers/Data/Application/682B78F7-D818-4BA3-B538-7D0D8E179735/Library/Caches/cwtools/courseware/2017-06-27/9AD8A349FA044E6FB379649370185397/resource/vedio1498556213.mp4
ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
built with Apple LLVM version 8.1.0 (clang-802.0.41)
configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libavresample 3. 5. 0 / 3. 5. 0
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/temp/Library/Developer/CoreSimulator/Devices/51C23BB1-86A1-4787-90DD-81D855E2A372/data/Containers/Data/Application/682B78F7-D818-4BA3-B538-7D0D8E179735/Library/Caches/cwtools/courseware/2017-06-27/9AD8A349FA044E6FB379649370185397/resource/vedio1498556213.mp4':
Metadata:
major_brand : mp42
minor_version : 1
compatible_brands: mp41mp42isom
creation_time : 2017-06-27T09:37:16.000000Z
location : +22.5365+114.0604+30.037994/
Duration: 00:00:11.31, start: 0.000000, bitrate: 831 kb/s
Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 85 kb/s (default)
Metadata:
creation_time : 2017-06-27T09:37:16.000000Z
handler_name : Core Media Audio
Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 568x320 [SAR 1:1 DAR 71:40], 740 kb/s, 29.98 fps, 29.97 tbr, 600 tbn, 1200 tbc (default)
Metadata:
rotate : 90
creation_time : 2017-06-27T09:37:16.000000Z
handler_name : Core Media Video
Side data:
displaymatrix: rotation of -90.00 degrees
AVAssetExportPreset960x540
tempdeMac-mini:V3.6.4 temp$ ffmpeg -i /Users/temp/Downloads/原/cwtools/courseware/2017-08-07/615EFBC619944BD9B76E5F9A58130317/resource/vedio1502073376.mp4
ffmpeg version 3.3 Copyright (c) 2000-2017 the FFmpeg developers
built with Apple LLVM version 8.1.0 (clang-802.0.41)
configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libavresample 3. 5. 0 / 3. 5. 0
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/temp/Downloads/原/cwtools/courseware/2017-08-07/615EFBC619944BD9B76E5F9A58130317/resource/vedio1502073376.mp4':
Metadata:
major_brand : mp42
minor_version : 1
compatible_brands: mp41mp42isom
creation_time : 2017-08-07T02:36:13.000000Z
Duration: 00:00:12.33, start: 0.000000, bitrate: 3815 kb/s
Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 82 kb/s (default)
Metadata:
creation_time : 2017-08-07T02:36:13.000000Z
handler_name : Core Media Audio
Stream #0:1(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 540x960, 3728 kb/s, 15 fps, 15 tbr, 600 tbn, 1200 tbc (default)
Metadata:
creation_time : 2017-08-07T02:36:13.000000Z
handler_name : Core Media Video