[FFmpeg-devel] [PATCH v3 2/2] lavc/get_buffer: Add a warning on failed allocation from a fixed pool

[Mark Thompson]

For hardware cases where we are forced to have a fixed pool of frames
allocated up-front (such as array textures on decoder output), suggest
a possible workaround to the user if an allocation fails because the
pool is exhausted.
---
Perhaps helpful; any thoughts?

The warning comes out before any errors, looking like:

[mpeg2video @ 0x560ff51b4600] Failed to allocate a vaapi/nv12 frame from a fixed pool of hardware frames.
[mpeg2video @ 0x560ff51b4600] Consider setting extra_hw_frames to a larger value (currently set to 8, giving a pool size of 14).
[mpeg2video @ 0x560ff51b4600] get_buffer() failed
[vist#0:0/mpeg2video @ 0x560ff5199840] [dec:mpeg2video @ 0x560ff51b3b40] Error submitting packet to decoder: Operation not permitted

  libavcodec/get_buffer.c | 16 ++++++++++++++++
  libavcodec/internal.h   |  6 ++++++
  2 files changed, 22 insertions(+)

diff --git a/libavcodec/get_buffer.c b/libavcodec/get_buffer.c
index 46c20781af..9b35fde7c6 100644
--- a/libavcodec/get_buffer.c
+++ b/libavcodec/get_buffer.c
@@ -257,6 +257,22 @@ int avcodec_default_get_buffer2(AVCodecContext *avctx, AVFrame *frame, int flags

      if (avctx->hw_frames_ctx) {
          ret = av_hwframe_get_buffer(avctx->hw_frames_ctx, frame, 0);
+        if (ret == AVERROR(ENOMEM)) {
+            AVHWFramesContext *frames_ctx =
+                (AVHWFramesContext*)avctx->hw_frames_ctx->data;
+            if (frames_ctx->initial_pool_size > 0 &&
+                !avctx->internal->warned_on_failed_allocation_from_fixed_pool) {
+                av_log(avctx, AV_LOG_WARNING, "Failed to allocate a %s/%s "
+                       "frame from a fixed pool of hardware frames.\n",
+                       av_get_pix_fmt_name(frames_ctx->format),
+                       av_get_pix_fmt_name(frames_ctx->sw_format));
+                av_log(avctx, AV_LOG_WARNING, "Consider setting "
+                       "extra_hw_frames to a larger value "
+                       "(currently set to %d, giving a pool size of %d).\n",
+                       avctx->extra_hw_frames, frames_ctx->initial_pool_size);
+                avctx->internal->warned_on_failed_allocation_from_fixed_pool = 1;
+            }
+        }
          frame->width  = avctx->coded_width;
          frame->height = avctx->coded_height;
          return ret;
diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index 04f7cebdcb..64fe0122c8 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -144,6 +144,12 @@ typedef struct AVCodecInternal {
  #if CONFIG_LCMS2
      FFIccContext icc; /* used to read and write embedded ICC profiles */
  #endif
+
+    /**
+     * Set when the user has been warned about a failed allocation from
+     * a fixed frame pool.
+     */
+    int warned_on_failed_allocation_from_fixed_pool;
  } AVCodecInternal;

  /**
-- 
2.43.0