Add V4L2M2M support using SDL renderer

Note: This requires FFmpeg master to work, since it depends on:
https://github.com/FFmpeg/FFmpeg/commit/d61cf1b1ebc2477749d7d7825a072400ed24af9

app/streaming/video/ffmpeg.cpp

@@ -543,6 +543,7 @@ bool FFmpegVideoDecoder::initialize(PDECODER_PARAMETERS params)
 #endif
 
 #ifdef HAVE_DRM
+        {
             // RKMPP is a hardware accelerated decoder that outputs DRI PRIME buffers
             AVCodec* rkmppDecoder;
 
@@ -558,6 +559,26 @@ bool FFmpegVideoDecoder::initialize(PDECODER_PARAMETERS params)
                                           []() -> IFFmpegRenderer* { return new DrmRenderer(); })) {
                 return true;
             }
+        }
+#endif
+
+#ifdef Q_OS_LINUX
+        {
+            AVCodec* v4l2Decoder;
+
+            if (params->videoFormat & VIDEO_FORMAT_MASK_H264) {
+                v4l2Decoder = avcodec_find_decoder_by_name("h264_v4l2m2m");
+            }
+            else {
+                v4l2Decoder = avcodec_find_decoder_by_name("hevc_v4l2m2m");
+            }
+
+            if (v4l2Decoder != nullptr &&
+                    tryInitializeRenderer(v4l2Decoder, params, nullptr,
+                                          []() -> IFFmpegRenderer* { return new SdlRenderer(); })) {
+                return true;
+            }
+        }
 #endif
 
         // Look for the first matching hwaccel hardware decoder (pass 1)