vcodec mmal decoding
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**Describe The Problem:**
<!-- A clear and concise description of what the bug is. -->
For a single camera, I couldn't get the mmal hardware decoder to work.
mmal_vc_port_info_set and mmal_vc_port_set_format are failing. Any idea why?
**To Reproduce:**
<!-- Steps to reproduce the behavior. -->
add -vcodec h264_mmal to input config
**Logs:**
<!-- Bug reports that do not contain logs may be closed without warning. -->

```
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info] ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   built with gcc 6.3.0 (Raspbian 6.3.0-18+rpi1+deb9u1) 20170516
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   configuration: --pkgconfigdir=/build/workspace/lib/pkgconfig --prefix=/build/workspace --pkg-config-flags=--static --extra-cflags=-I/build/workspace/include --extra-ldflags=-L/build/workspace/lib --extra-libs='-lpthread -lm' --enable-static --disable-debug --disable-shared --disable-ffplay --disable-doc --enable-openssl --enable-gpl --enable-version3 --enable-nonfree --enable-pthreads --enable-libvpx --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libx264 --enable-runtime-cpudetect --enable-libfdk-aac --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-decoder=h264 --enable-network --enable-protocol=tcp --enable-libspeex --enable-demuxer=rtsp --enable-omx-rpi --enable-mmal --enable-indev=alsa --enable-outdev=alsa
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libavutil      56. 51.100 / 56. 51.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libavcodec     58. 91.100 / 58. 91.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libavformat    58. 45.100 / 58. 45.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libavdevice    58. 10.100 / 58. 10.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libavfilter     7. 85.100 /  7. 85.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libswscale      5.  7.100 /  5.  7.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libswresample   3.  7.100 /  3.  7.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   libpostproc    55.  7.100 / 55.  7.100
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [tcp @ 0x35b0750] [verbose] Starting connection attempt to 192.168.1.23 port 554
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [tcp @ 0x35b0750] [verbose] Successfully connected to 192.168.1.23 port 554
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [rtsp @ 0x35ae740] [verbose] SDP:
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] v=0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] o=- 2251938200 2251938200 IN IP4 0.0.0.0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] s=Media Server
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] c=IN IP4 0.0.0.0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] t=0 0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=control:*
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=packetization-supported:DH
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=rtppayload-supported:DH
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=range:npt=now-
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] m=video 0 RTP/AVP 96
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=control:trackID=0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=framerate:20.000000
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=rtpmap:96 H264/90000
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=fmtp:96 packetization-mode=1;profile-level-id=640032;sprop-parameter-sets=Z2QAMqw0yAJACj/wFuAgICgAAB9AAATiB0MAAQRcAABBFqXeXGhgACCLgAAIItS7y4UA,aO48MAA=
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] a=recvonly
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [rtsp @ 0x35ae740] [verbose] setting jitter buffer size to 0
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] [h264 @ 0x35b1dc0] [verbose] Reinit context to 2304x1296, pix_fmt: yuvj420p
[9/25/2020, 1:00:20 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:20 AM] [LAXSS] current system temp: 36 C
[9/25/2020, 1:00:22 AM] [LAXDISKSTATION] current system temp: 35 C
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info] Input #0, rtsp, from 'rtsp://Homebridge:Homebridge@192.168.1.23/cam/realmonitor?channel=1&subtype=0':
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   Metadata:
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]     title           : Media Server
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   Duration: N/A, start: 0.450000, bitrate: N/A
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]     Stream #0:0: Video: h264 (High), 1 reference frame, yuvj420p(pc, bt709, progressive, left), 2304x1296 [SAR 1:1 DAR 16:9], 20 fps, 20 tbr, 90k tbn, 40 tbc
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] mmal: mmal_vc_port_info_set: failed to set port info (2:0): EINVAL
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] mmal: mmal_vc_port_set_format: mmal_vc_port_info_set failed 0x377c7d0 (EINVAL)
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] mmal: mmal_port_disable: port vc.ril.video_decode:in:0(H264)(0x377c7d0) is not enabled
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] mmal: mmal_port_disable: port vc.ril.video_decode:out:0(0x377cae0) is not enabled
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] mmal: mmal_port_disable: port vc.ril.video_decode:ctr:0(0x35cd1a0) is not enabled
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info] Stream mapping:
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [info]   Stream #0:0 -> #0:0 (h264 (h264_mmal) -> h264 (libx264))
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [error] Error while opening decoder for input stream #0:0 : Unknown error occurred
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] [AVIOContext @ 0x35c9640] [verbose] Statistics: 0 seeks, 0 writeouts
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] 
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] FFmpeg exited with code: 1 and signal: null (Error)
[9/25/2020, 1:00:22 AM] [Camera FFmpeg] [Ara Sokak Kamera] Stopped video stream.

```

**Homebridge Config:**

```json
                {
                    "name": "Cam3",
                    "manufacturer": "DAHUA",
                    "model": "IPC-HFW1320S",
                    "serialNumber": "3X058D5PAG00056",
                    "firmwareRevision": "2.620.0000004.0.R, Build Date: 2019-11-30",
                    "unbridge": true,
                    "videoConfig": {
                        "source": "-rtsp_transport tcp -vcodec h264_mmal -i rtsp://Homebridge:Homebridge@192.168.1.23/cam/realmonitor?channel=1&subtype=0",
                        "maxStreams": 3,
                        "vcodec": "libx264",
                        "audio": false,
                        "debug": true
                    }
                },
```

**Screenshots:**
<!-- If applicable, add screenshots to help explain your problem. -->

**Environment:**

* **Node.js Version**: v12.18.3
* **NPM Version**: v6.14.8
* **Homebridge Version**: 1.2.3
* **Homebridge Camera FFmpeg Version**: v3.0.3
* **Homebridge Config UI X Plugin Version**: v4.27.1
* **Operating System**: Raspbian GNU/Linux Buster (10)


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