当我们使用HEVC+RTP时，ffmpeg工作正常。该流由网络摄像头捕获。
ffmpeg -f dshow -rtbufsize 100M -f vfwcap -i "0" -strict experimental -c:v hevc_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test
输出如下：
frame= 355 fps= 37 q=-0.0 size=N/A time=00:00:11.27 bitrate=N/A dup=159 drop=0 speed=1.18x
然后我们切换到VP9+RTSP。
ffmpeg -f dshow -rtbufsize 100M -f vfwcap -i "0" -strict experimental -c:v libvpx-vp9 -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test
fps和速度看起来太慢：
frame= 263 fps=9.5 q=0.0 size=N/A time=00:00:07.94 bitrate=N/A dup=119 drop=0 speed=0.288x
然后我们用ffplay播放流。有很多错误消息，视频似乎被冻结了。
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available0B f=0/0
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
最后，我们尝试了硬件VP9编码器。
ffmpeg -f dshow -rtbufsize 100M -f vfwcap -i "0" -strict experimental -c:v vp9_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test
它不起作用。
[swscaler @ 0000021e88df9fc0] deprecated pixel format used, make sure you did set range correctly
[vp9_qsv @ 0000021e8687df80] Selected ratecontrol mode is unsupported
[vp9_qsv @ 0000021e8687df80] Low power mode is unsupported
[vp9_qsv @ 0000021e8687df80] Current frame rate is unsupported
[vp9_qsv @ 0000021e8687df80] Current picture structure is unsupported
[vp9_qsv @ 0000021e8687df80] Current resolution is unsupported
[vp9_qsv @ 0000021e8687df80] Current pixel format is unsupported
[vp9_qsv @ 0000021e8687df80] some encoding parameters are not supported by the QSV runtime. Please double check the input parameters.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!
那么，我们如何才能成功地处理VP9+RTSP呢？
我在这方面绝非权威，但我的处境与你相似。如果我正确理解这个GitHub问题；第9代；英特尔GPU-"；Kaby Lake，Coffee Lake，Whiskey Lake，Comet Lake"每个维基百科(我认为对应于7xxx到10xxx(都支持VP9编码的硬件，但Windows驱动程序并没有公开这一功能供Media SDK利用。我认为我们看到的错误消息反映了这样一个事实，即QSV编码在我们的特定CPU型号和操作系统上不可用。
由于某些原因，功能在Linux上是可用的。我已经看到几个消息来源说VA API(vp9_vaapi(应该在这些"；第9代；处理器；QSV驱动程序(vp9_qsv(也可能在Linux中工作。我还没有机会尝试一下。