# 關於Youtube VP9/H264在intel HD530上硬解的那件事
###### tags: `技術文`

# 實驗設備
- 筆電 i5-6200U ~~(Intel HD530)~~ Intel 530 + Nvdia 930M
- 桌電 i7-6700 (Intel 520)

# youtube codecs
查看youtube影片所使用的編碼格式: `statistics->codecs:VP9`

chrome flags無法更動，固YOUTUBE維持VP9輸出
>[name=[e-mail] ][time=Jul 7 2015][color=orange]["Given the presence of the h264ify extension and recent performance numbers for vp9, it doesn't make sense to implement this.""](https://bugs.chromium.org/p/chromium/issues/detail?id=459407)

可裝`h264ify`套件讓chrome儘量用h.264

# hardware encode/decode support
硬體編/解碼仰賴獨立電路或CUDA，各家GPU支援程度:
- [NVIDIA Decoder](https://developer.nvidia.com/video-encode-decode-gpu-support-matrix)
- [Intel HD530](https://en.wikichip.org/wiki/intel/hd_graphics/530)
- [AMD](https://en.wikipedia.org/wiki/Unified_Video_Decoder)

Support|H264|H265|VP9
---|---|---|---
Intel HD530|O|O|O
Geforce 930M|O|X|X
> Geforce 930M based on 840

買筆電+NVDIA獨顯當羊

:::info
發哥[Dimensity 1000](https://i.mediatek.com/mediatek-5g)支援硬解ㄛ
:::

# software/browser support
- VLC相關設定
- 視訊->output:自動
　 
- 編解碼器->VM-API(with/without DRM)
　 

- Browser:除了硬體支援外，在瀏覽器使用硬解需要瀏覽器也支持
- Microsoft edge
- 目前所知能硬解VP9唯一瀏覽器
- chrome
- `chrome://gpu/` 查看相關資訊

        Graphics Feature Status
            Canvas: Hardware accelerated
            Flash: Hardware accelerated
            Flash Stage3D: Hardware accelerated
            Flash Stage3D Baseline profile: Hardware accelerated
            Compositing: Hardware accelerated
            Multiple Raster Threads: Enabled
            Out-of-process Rasterization: Disabled
            OpenGL: Enabled
            Hardware Protected Video Decode: Unavailable**
            Rasterization: Software only. Hardware acceleration disabled
            Skia Renderer: Enabled
            Video Decode: Unavailable
            Vulkan: Disabled
            WebGL: Hardware accelerated
            WebGL2: Hardware accelerated
            
        Problems Detected
            Accelerated video decode is unavailable on Linux: 137247, 1032907
            Disabled Features: accelerated_video_decode**
            Protected video decoding with swap chain is for Windows and Intel only
            Disabled Features: protected_video_decode**
            
        真蚌

# 取得影片
使用`youtube-dl`查詢影片資訊

~$ youtube-dl -F https://www.youtube.com/watch?v=ftlvreFtA2A
[youtube] ftlvreFtA2A: Downloading webpage
[info] Available formats for ftlvreFtA2A:
format code  extension  resolution note
249          webm       audio only tiny   56k , opus @ 50k (48000Hz), 20.09MiB
250          webm       audio only tiny   75k , opus @ 70k (48000Hz), 26.61MiB
140          m4a        audio only tiny  131k , m4a_dash container, mp4a.40.2@128k (44100Hz), 52.22MiB
251          webm       audio only tiny  144k , opus @160k (48000Hz), 52.26MiB
394          mp4        256x144    144p   86k , av01.0.00M.08, 30fps, video only, 27.83MiB
160          mp4        256x144    144p  106k , avc1.4d400c, 30fps, video only, 17.08MiB
278          webm       256x144    144p  112k , webm container, vp9, 30fps, video only, 36.31MiB
395          mp4        426x240    240p  198k , av01.0.00M.08, 30fps, video only, 55.32MiB
133          mp4        426x240    240p  243k , avc1.4d4015, 30fps, video only, 37.24MiB
242          webm       426x240    240p  244k , vp9, 30fps, video only, 70.93MiB
396          mp4        640x360    360p  369k , av01.0.01M.08, 30fps, video only, 110.67MiB
243          webm       640x360    360p  427k , vp9, 30fps, video only, 145.22MiB
134          mp4        640x360    360p  697k , avc1.4d401e, 30fps, video only, 134.15MiB
397          mp4        854x480    480p  710k , av01.0.04M.08, 30fps, video only, 210.85MiB
244          webm       854x480    480p  798k , vp9, 30fps, video only, 274.02MiB
135          mp4        854x480    480p 1347k , avc1.4d401f, 30fps, video only, 327.02MiB
398          mp4        1280x720   720p 1388k , av01.0.05M.08, 30fps, video only, 433.65MiB
247          webm       1280x720   720p 1601k , vp9, 30fps, video only, 589.98MiB
399          mp4        1920x1080  1080p 2491k , av01.0.08M.08, 30fps, video only, 752.58MiB
136          mp4        1280x720   720p 2716k , avc1.4d401f, 30fps, video only, 785.16MiB
248          webm       1920x1080  1080p 3023k , vp9, 30fps, video only, 1.03GiB
137          mp4        1920x1080  1080p 5114k , avc1.640028, 30fps, video only, 1.50GiB
400          mp4        2560x1440  1440p 8714k , av01.0.12M.08, 30fps, video only, 2.48GiB
271          webm       2560x1440  1440p 9247k , vp9, 30fps, video only, 3.37GiB
401          mp4        3840x2160  2160p 17495k , av01.0.12M.08, 30fps, video only, 5.13GiB
313          webm       3840x2160  2160p 18496k , vp9, 30fps, video only, 7.04GiB
18           mp4        640x360    360p  654k , avc1.42001E, 30fps, mp4a.40.2@ 96k (44100Hz), 268.98MiB
22           mp4        1280x720   720p 2036k , avc1.64001F, 30fps, mp4a.40.2@192k (44100Hz) (best)

每行標明封裝格式、解析度、編碼，例如這行
`401 mp4 3840x2160 2160p 17495k , av01.0.12M.08, 30fps, video only, 5.13GiB`
- `mp4`是封裝格式
- `av01`是編碼
- `3840x2160` 是解析度

有幾種不同的封裝格式
- avc1 (H.264)
- av01
> *[It was developed as a successor to VP9](https://en.wikipedia.org/wiki/AV1)*
> 未來取代vp9
- vp9

選定格式後使用`-f` 下載影片

~$ youtube-dl -f 137+140 https://www.youtube.com/watch?v=ftlvreFtA2A

# 實驗

有用內顯硬解用`intel_gpu_top`能看到video使用率

intel-gpu-top -  350/ 350 MHz;   95% RC6;  0.04 Watts;      145 irqs/s

      IMC reads:      842 MiB/s
     IMC writes:       77 MiB/s

          ENGINE      BUSY                                      MI_SEMA MI_WAIT
     Render/3D/0    1.18% |▍                                  |      0%      0%
       Blitter/0    0.00% |                                   |      0%      0%
         Video/0    0.00% |                                   |      0%      0%
  VideoEnhance/0    0.00% |                                   |      0%      0%

video format|Intel HD530 Video Engine Usage
---|---
1080p, avc1.640028, 30fps| 20~30%