在给客户进行故障排查时，使用 ffplay 去播放，希望看播放视频的分辨率，发现客户设置了 referer 防盗链，直接访问返回 http 状态码403。之前都是直接用 ffplay 来进行播放的，查了下帮助文档，发现参数太大，于是使用 grep 打法过滤了下发现可以指定–headers 来进行自定义 http 请求头。
➜ ~ ffplay --help | grep 'HTTP'
ffplay version 3.3 Copyright (c) 2003-2017 the FFmpeg developers
built with Apple LLVM version 8.1.0 (clang-802.0.42)
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-libx265 --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
-ffrtmphttp_tls <boolean> .D...... Use a HTTPS tunneling connection (RTMPTS). (default false)
-http_proxy <string> ED...... set HTTP proxy to tunnel through
-headers <string> ED...... set custom HTTP headers, can override built in default headers
-post_data <binary> ED...... set custom HTTP post data
-cookies <string> .D...... set cookies to be sent in applicable future requests, use newline delimited Set-Cookie HTTP field value syntax
-auth_type <int> ED...... HTTP authentication type (from 0 to 1) (default none)
basic ED...... HTTP basic authentication
-method <string> ED...... Override the HTTP method or set the expected HTTP method from a client
-listen <int> ED...... listen on HTTP (from 0 to 2) (default 0)
-http_proxy <string> ED...... set HTTP proxy to tunnel through
-headers <string> ED...... set custom HTTP headers, can override built in default headers
-post_data <binary> ED...... set custom HTTP post data
-cookies <string> .D...... set cookies to be sent in applicable future requests, use newline delimited Set-Cookie HTTP field value syntax
-auth_type <int> ED...... HTTP authentication type (from 0 to 1) (default none)
basic ED...... HTTP basic authentication
-method <string> ED...... Override the HTTP method or set the expected HTTP method from a client
-listen <int> ED...... listen on HTTP (from 0 to 2) (default 0)
http .D...... HTTP tunneling
http .D...... HTTP tunneling其中的
-headers <string> ED...... set custom HTTP headers, can override built in default headers就是我们想要的了，知道了用什么就好办了，直接
➜ ~ ffplay -headers 'referer:xxx.cn' http://xxxxx/a/11.m3u8
ffplay version 3.3 Copyright (c) 2003-2017 the FFmpeg developers
built with Apple LLVM version 8.1.0 (clang-802.0.42)
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-libx265 --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
[http @ 0x7fd5b2d93320] No trailing CRLF found in HTTP header.
Input #0, hls,applehttp, from 'http://xxxxx/a/11.m3u8':B f=0/0
Duration: 00:08:25.90, start: 1.466667, bitrate: 0 kb/s
Program 0
Metadata:
variant_bitrate : 0
Stream #0:0: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 720x1280 [SAR 1:1 DAR 9:16], 30 fps, 30 tbr, 90k tbn, 60 tbc
Metadata:
variant_bitrate : 0
Stream #0:1: Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, mono, fltp
Metadata:
variant_bitrate : 0
3.68 A-V: -0.034 fd= 0 aq= 13KB vq= 126KB sq= 0B f=0/0其中这段显示的是客户改视频文件视频的编码方式是 H264,yuv420p是使用的颜色空间其中，Y表示亮度，而U，V则与颜色相关，而420则分别对应着存储相应分量所占用的比特数之，720x1280是视频的分辨率，[SAR 1:1 DAR 9:16]是视频的大小是16比9，30 fps 就是帧率咯，tbr, 90k tbn, 60 tbc 这是表示在相应层上的时间单元，比如tbn=2997就相当于在视频流层把1s的时间分成了2997个时间单元，如此精细可以更好的与其他流比如音频流同步，对应着fps=29.97就表示每100个时间单元中有一帧。
Stream #0:0: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 720x1280 [SAR 1:1 DAR 9:16], 30 fps, 30 tbr, 90k tbn, 60 tbc对于多媒体这块了解不多，也就是在处理 cdn 问题的时候稍微了解下。
