From ef719dc9386612f76a1df2fbb60915b5fc0bed57 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sun, 25 Jul 2021 13:26:45 -0500
Subject: [PATCH] Cleanup and optimize FFmpeg code

---
 src/video/ffmpeg.c | 24 +++++++++++++-----------
 src/video/ffmpeg.h | 12 +-----------
 src/video/sdl.c    |  7 +++----
 src/video/x11.c    | 13 ++++++++-----
 4 files changed, 25 insertions(+), 31 deletions(-)

diff --git a/src/video/ffmpeg.c b/src/video/ffmpeg.c
index 764ea39..d34849a 100644
--- a/src/video/ffmpeg.c
+++ b/src/video/ffmpeg.c
@@ -80,20 +80,22 @@ int ffmpeg_init(int videoFormat, int width, int height, int perf_lvl, int buffer
     return -1;
   }
 
-  if (perf_lvl & DISABLE_LOOP_FILTER)
-    // Skip the loop filter for performance reasons
-    decoder_ctx->skip_loop_filter = AVDISCARD_ALL;
+  // Use low delay decoding
+  decoder_ctx->flags |= AV_CODEC_FLAG_LOW_DELAY;
 
-  if (perf_lvl & LOW_LATENCY_DECODE)
-    // Use low delay single threaded encoding
-    decoder_ctx->flags |= AV_CODEC_FLAG_LOW_DELAY;
+  // Allow display of corrupt frames and frames missing references
+  decoder_ctx->flags |= AV_CODEC_FLAG_OUTPUT_CORRUPT;
+  decoder_ctx->flags2 |= AV_CODEC_FLAG2_SHOW_ALL;
 
-  if (perf_lvl & SLICE_THREADING)
+  // Report decoding errors to allow us to request a key frame
+  decoder_ctx->err_recognition = AV_EF_EXPLODE;
+
+  if (perf_lvl & SLICE_THREADING) {
     decoder_ctx->thread_type = FF_THREAD_SLICE;
-  else
-    decoder_ctx->thread_type = FF_THREAD_FRAME;
-
-  decoder_ctx->thread_count = thread_count;
+    decoder_ctx->thread_count = thread_count;
+  } else {
+    decoder_ctx->thread_count = 1;
+  }
 
   decoder_ctx->width = width;
   decoder_ctx->height = height;
diff --git a/src/video/ffmpeg.h b/src/video/ffmpeg.h
index 1fab434..a6e9af8 100644
--- a/src/video/ffmpeg.h
+++ b/src/video/ffmpeg.h
@@ -21,18 +21,8 @@
 
 #include <libavcodec/avcodec.h>
 
-// Disables the deblocking filter at the cost of image quality
-#define DISABLE_LOOP_FILTER 0x1
-// Uses the low latency decode flag (disables multithreading)
-#define LOW_LATENCY_DECODE 0x2
-// Threads process each slice, rather than each frame
+// Enable multi-threaded decoding
 #define SLICE_THREADING 0x4
-// Uses nonstandard speedup tricks
-#define FAST_DECODE 0x8
-// Uses bilinear filtering instead of bicubic
-#define BILINEAR_FILTERING 0x10
-// Uses a faster bilinear filtering with lower image quality
-#define FAST_BILINEAR_FILTERING 0x20
 // Uses hardware acceleration
 #define VDPAU_ACCELERATION 0x40
 #define VAAPI_ACCELERATION 0x80
diff --git a/src/video/sdl.c b/src/video/sdl.c
index ef31291..992287a 100644
--- a/src/video/sdl.c
+++ b/src/video/sdl.c
@@ -29,13 +29,12 @@
 #include <stdbool.h>
 
 #define DECODER_BUFFER_SIZE 92*1024
+#define SLICES_PER_FRAME 4
 
 static char* ffmpeg_buffer;
 
 static int sdl_setup(int videoFormat, int width, int height, int redrawRate, void* context, int drFlags) {
-  int avc_flags = SLICE_THREADING;
-
-  if (ffmpeg_init(videoFormat, width, height, avc_flags, SDL_BUFFER_FRAMES, sysconf(_SC_NPROCESSORS_ONLN)) < 0) {
+  if (ffmpeg_init(videoFormat, width, height, SLICE_THREADING, SDL_BUFFER_FRAMES, SLICES_PER_FRAME) < 0) {
     fprintf(stderr, "Couldn't initialize video decoding\n");
     return -1;
   }
@@ -93,5 +92,5 @@ DECODER_RENDERER_CALLBACKS decoder_callbacks_sdl = {
   .setup = sdl_setup,
   .cleanup = sdl_cleanup,
   .submitDecodeUnit = sdl_submit_decode_unit,
-  .capabilities = CAPABILITY_SLICES_PER_FRAME(4) | CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC | CAPABILITY_DIRECT_SUBMIT,
+  .capabilities = CAPABILITY_SLICES_PER_FRAME(SLICES_PER_FRAME) | CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC | CAPABILITY_DIRECT_SUBMIT,
 };
diff --git a/src/video/x11.c b/src/video/x11.c
index e15ecb1..13bf3f7 100644
--- a/src/video/x11.c
+++ b/src/video/x11.c
@@ -40,6 +40,7 @@
 #define DECODER_BUFFER_SIZE 92*1024
 #define X11_VDPAU_ACCELERATION ENABLE_HARDWARE_ACCELERATION_1
 #define X11_VAAPI_ACCELERATION ENABLE_HARDWARE_ACCELERATION_2
+#define SLICES_PER_FRAME 4
 
 static char* ffmpeg_buffer = NULL;
 
@@ -124,13 +125,15 @@ int x11_setup(int videoFormat, int width, int height, int redrawRate, void* cont
   }
   XFlush(display);
 
-  int avc_flags = SLICE_THREADING;
+  int avc_flags;
   if (drFlags & X11_VDPAU_ACCELERATION)
-    avc_flags |= VDPAU_ACCELERATION;
+    avc_flags = VDPAU_ACCELERATION;
   else if (drFlags & X11_VAAPI_ACCELERATION)
-    avc_flags |= VAAPI_ACCELERATION;
+    avc_flags = VAAPI_ACCELERATION;
+  else
+    avc_flags = SLICE_THREADING;
 
-  if (ffmpeg_init(videoFormat, width, height, avc_flags, 2, 2) < 0) {
+  if (ffmpeg_init(videoFormat, width, height, avc_flags, 2, SLICES_PER_FRAME) < 0) {
     fprintf(stderr, "Couldn't initialize video decoding\n");
     return -1;
   }
@@ -185,7 +188,7 @@ DECODER_RENDERER_CALLBACKS decoder_callbacks_x11 = {
   .setup = x11_setup,
   .cleanup = x11_cleanup,
   .submitDecodeUnit = x11_submit_decode_unit,
-  .capabilities = CAPABILITY_SLICES_PER_FRAME(4) | CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC | CAPABILITY_DIRECT_SUBMIT,
+  .capabilities = CAPABILITY_SLICES_PER_FRAME(SLICES_PER_FRAME) | CAPABILITY_REFERENCE_FRAME_INVALIDATION_AVC | CAPABILITY_DIRECT_SUBMIT,
 };
 
 DECODER_RENDERER_CALLBACKS decoder_callbacks_x11_vdpau = {