[FFmpeg-devel] [PATCH] lavc/decode: allow users to shrink the hw frames pool size, if they so desire.

[Timo Rothenpieler]

---
 libavcodec/decode.c        | 9 +++++----
 libavcodec/options_table.h | 2 +-
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/libavcodec/decode.c b/libavcodec/decode.c
index c89c77c43a..08ae8788a2 100644
--- a/libavcodec/decode.c
+++ b/libavcodec/decode.c
@@ -1256,10 +1256,11 @@ int avcodec_get_hw_frames_parameters(AVCodecContext *avctx,
         AVHWFramesContext *frames_ctx = (AVHWFramesContext*)frames_ref->data;
 
         if (frames_ctx->initial_pool_size) {
-            // If the user has requested that extra output surfaces be
-            // available then add them here.
-            if (avctx->extra_hw_frames > 0)
-                frames_ctx->initial_pool_size += avctx->extra_hw_frames;
+            // If the user has requested extra/fewer output surfaces be
+            // available then add/substract them here.
+            frames_ctx->initial_pool_size += avctx->extra_hw_frames;
+            if (avctx->extra_hw_frames < 0)
+                av_log(avctx, AV_LOG_WARNING, "Decreasing hwaccel frame pool size!\n");
 
             // If frame threading is enabled then an extra surface per thread
             // is also required.
diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
index 099261e168..af0ab1cfe0 100644
--- a/libavcodec/options_table.h
+++ b/libavcodec/options_table.h
@@ -478,7 +478,7 @@ static const AVOption avcodec_options[] = {
 {"ignore_level", "ignore level even if the codec level used is unknown or higher than the maximum supported level reported by the hardware driver", 0, AV_OPT_TYPE_CONST, { .i64 = AV_HWACCEL_FLAG_IGNORE_LEVEL }, INT_MIN, INT_MAX, V | D, "hwaccel_flags" },
 {"allow_high_depth", "allow to output YUV pixel formats with a different chroma sampling than 4:2:0 and/or other than 8 bits per component", 0, AV_OPT_TYPE_CONST, {.i64 = AV_HWACCEL_FLAG_ALLOW_HIGH_DEPTH }, INT_MIN, INT_MAX, V | D, "hwaccel_flags"},
 {"allow_profile_mismatch", "attempt to decode anyway if HW accelerated decoder's supported profiles do not exactly match the stream", 0, AV_OPT_TYPE_CONST, {.i64 = AV_HWACCEL_FLAG_ALLOW_PROFILE_MISMATCH }, INT_MIN, INT_MAX, V | D, "hwaccel_flags"},
-{"extra_hw_frames", "Number of extra hardware frames to allocate for the user", OFFSET(extra_hw_frames), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, V|D },
+{"extra_hw_frames", "Number of extra hardware frames to allocate for the user, negative values are supported at own risk", OFFSET(extra_hw_frames), AV_OPT_TYPE_INT, { .i64 = 0 }, INT_MIN, INT_MAX, V|D },
 {NULL},
 };
 
-- 
2.17.0