風信建站新的開發項目中引用視頻流技術，為了有效解決大視頻在數據請求過程中加載過慢的問題，經過多次測試，決定使用m3u8格式做為視頻流的格式，那么mp4和m3u8格式的視頻各有什么缺點和優點呢？
mp4視頻格式有以下優點：
1：跨平臺支持，即支持pc端和移動端（ios和安卓）。
2：該格式性能優越。
mp4視頻的缺點：
1：視頻時間長度過長時，在移動端會消耗大量的流量，但隨著互聯網流量資費的發展（將來流量是包月/年的，每月交一定費用，流量無限使用。）該缺點將不再存在。
2：視頻文件相對大一些。對于服務器的空間占用方面會有一定壓力。
視頻本身的要求
1：視頻轉碼格式需要是h.264
2：音頻轉碼格式需要是AAC
3：如果考慮到需要支持在PC端低版本IE（IE9及以下）的環境中（在該環境中只能使用flashplayer播放）支持視頻請求未下載到用戶本地緩存區的內容播放。則需要視頻本身存在關鍵幀和關鍵時間點（服務器方面也有要求）。
m3u8的優點：
1：因為視頻被切成多個.ts文件，所以不需要考慮元數據的問題，并且可以分段加載。
2：在PC端使用flashplayer播放時可以實現視頻的絕對加密。也就是視頻即使是被下載到用戶本地也無法使用。
m3u8的缺點
正常情況下不支持PC端的播放。ckplayer做了兼容是支持在pc端播放的，前提是pc端瀏覽器需要支持flashplayer
使用m3u8我們需要將mp4視頻進行轉碼，命令如下：
ffmpeg -i 2.mp4 -codec copy -vbsf h264_mp4toannexb -map 0 -f segment -segment_list m3u8/2.m3u8 -segment_time 10 m3u8/out%03d.ts
G:\phpstudy_pro\wwwroot\ebiaoip-v\public>ffmpeg -i 2.mp4 -codec copy -vbsf h264_
mp4toannexb -map 0 -f segment -segment_list m3u8/2.m3u8 -segment_time 10 m3u8/ou
t%03d.ts
ffmpeg version n4.3.1-23-gc19641b2e2 Copyright (c) 2000-2020 the FFmpeg develope
rs
built with gcc 9.3-win32 (GCC) 20200320
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-conf
ig=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw
32 --enable-gpl --enable-version3 --disable-debug --enable-iconv --enable-zlib -
-enable-libxml2 --enable-libfreetype --enable-libfribidi --enable-gmp --enable-l
zma --enable-fontconfig --enable-opencl --enable-libvmaf --disable-vulkan --enab
le-libvorbis --enable-amf --enable-libaom --enable-avisynth --enable-libdav1d --
enable-libdavs2 --enable-ffnvcodec --enable-cuda-llvm --disable-libglslang --ena
ble-libass --enable-libbluray --enable-libmp3lame --enable-libopus --enable-libt
heora --enable-libvpx --enable-libwebp --enable-libmfx --enable-libopencore-amrn
b --enable-libopencore-amrwb --enable-libopenjpeg --enable-librav1e --enable-lib
rubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --en
able-libtwolame --enable-libvidstab --enable-libx264 --enable-libx265 --enable-l
ibxavs2 --enable-libxvid --enable-libzimg --extra-cflags=-DLIBTWOLAME_STATIC --e
xtra-cxxflags= --extra-ldflags=-pthread --extra-libs=-lgomp
libavutil 56. 51.100 / 56. 51.100
libavcodec 58. 91.100 / 58. 91.100
libavformat 58. 45.100 / 58. 45.100
libavdevice 58. 10.100 / 58. 10.100
libavfilter 7. 85.100 / 7. 85.100
libswscale 5. 7.100 / 5. 7.100
libswresample 3. 7.100 / 3. 7.100
libpostproc 55. 7.100 / 55. 7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '2.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf57.58.101
Duration: 00:04:10.13, start: 0.000000, bitrate: 161 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x368 [
SAR 1:1 DAR 40:23], 107 kb/s, 20 fps, 20 tbr, 10240 tbn, 80 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, flt
p, 48 kb/s (default)
Metadata:
handler_name : SoundHandler
[segment @ 00000000004b8d00] Opening 'm3u8/out000.ts' for writing
Output #0, segment, to 'm3u8/out%03d.ts':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf58.45.100
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x368 [
SAR 1:1 DAR 40:23], q=2-31, 107 kb/s, 20 fps, 20 tbr, 90k tbn, 40 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, flt
p, 48 kb/s (default)
Metadata:
handler_name : SoundHandler
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out001.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out002.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out003.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out004.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out005.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out006.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out007.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out008.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out009.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out010.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out011.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out012.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out013.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out014.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out015.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out016.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out017.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out018.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/out019.ts' for writing
[segment @ 00000000004b8d00] Opening 'm3u8/2.m3u8.tmp' for writing
frame= 4996 fps=0.0 q=-1.0 Lsize=N/A time=00:04:10.09 bitrate=N/A speed=1.44e+03
x
video:3274kB audio:1468kB subtitle:0kB other streams:0kB global headers:0kB muxi
ng overhead: unknown
轉碼成功之后就可以在播放器中使用，加載速度快多啦！
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