[FFmpeg-devel] [PATCH 2/2] lavc/vaapi_decode: recreate hw_frames_ctx without destroy va_context

[Linjie Fu]

VP9 allows resolution changes per frame. Currently in VAAPI, resolution
changes leads to va context destroy and reinit. This will cause
reference frame surface lost and produce garbage.

As libva allows re-create surface separately without changing the
context, this issue could be handled by only recreating hw_frames_ctx.

Could be verified by:
ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -i
./resolutions.ivf
-pix_fmt p010le -f rawvideo -vframes 20 -y vaapi.yuv

Signed-off-by: Linjie Fu <linjie.fu at intel.com>
---
 libavcodec/decode.c       |  8 ++++----
 libavcodec/vaapi_decode.c | 40 ++++++++++++++++++++++------------------
 2 files changed, 26 insertions(+), 22 deletions(-)

diff --git a/libavcodec/decode.c b/libavcodec/decode.c
index 0863b82..a81b857 100644
--- a/libavcodec/decode.c
+++ b/libavcodec/decode.c
@@ -1254,7 +1254,6 @@ int ff_decode_get_hw_frames_ctx(AVCodecContext *avctx,
 
     frames_ctx = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
 
-
     if (frames_ctx->initial_pool_size) {
         // We guarantee 4 base work surfaces. The function above guarantees 1
         // (the absolute minimum), so add the missing count.
@@ -1333,7 +1332,7 @@ static int hwaccel_init(AVCodecContext *avctx,
         return AVERROR_PATCHWELCOME;
     }
 
-    if (hwaccel->priv_data_size) {
+    if (hwaccel->priv_data_size && !avctx->internal->hwaccel_priv_data) {
         avctx->internal->hwaccel_priv_data =
             av_mallocz(hwaccel->priv_data_size);
         if (!avctx->internal->hwaccel_priv_data)
@@ -1397,8 +1396,9 @@ int ff_get_format(AVCodecContext *avctx, const enum AVPixelFormat *fmt)
 
     for (;;) {
         // Remove the previous hwaccel, if there was one.
-        hwaccel_uninit(avctx);
-
+        // VAAPI allows reinit hw_frames_ctx only
+        if (choices[0] != AV_PIX_FMT_VAAPI_VLD)
+            hwaccel_uninit(avctx);
         user_choice = avctx->get_format(avctx, choices);
         if (user_choice == AV_PIX_FMT_NONE) {
             // Explicitly chose nothing, give up.
diff --git a/libavcodec/vaapi_decode.c b/libavcodec/vaapi_decode.c
index 69512e1..13f0cf0 100644
--- a/libavcodec/vaapi_decode.c
+++ b/libavcodec/vaapi_decode.c
@@ -613,8 +613,10 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
     VAStatus vas;
     int err;
 
-    ctx->va_config  = VA_INVALID_ID;
-    ctx->va_context = VA_INVALID_ID;
+    if (!ctx->va_config && !ctx->va_context){
+        ctx->va_config  = VA_INVALID_ID;
+        ctx->va_context = VA_INVALID_ID;
+    }
 
 #if FF_API_STRUCT_VAAPI_CONTEXT
     if (avctx->hwaccel_context) {
@@ -642,7 +644,6 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
         // present, so set it here to avoid the behaviour changing.
         ctx->hwctx->driver_quirks =
             AV_VAAPI_DRIVER_QUIRK_RENDER_PARAM_BUFFERS;
-
     }
 #endif
 
@@ -655,7 +656,8 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
                "context: %#x/%#x.\n", ctx->va_config, ctx->va_context);
     } else {
 #endif
-
+    // Get a new hw_frames_ctx even if there is already one
+    // recreate surface without reconstuct va_context
     err = ff_decode_get_hw_frames_ctx(avctx, AV_HWDEVICE_TYPE_VAAPI);
     if (err < 0)
         goto fail;
@@ -670,21 +672,23 @@ int ff_vaapi_decode_init(AVCodecContext *avctx)
     if (err)
         goto fail;
 
-    vas = vaCreateContext(ctx->hwctx->display, ctx->va_config,
-                          avctx->coded_width, avctx->coded_height,
-                          VA_PROGRESSIVE,
-                          ctx->hwfc->surface_ids,
-                          ctx->hwfc->nb_surfaces,
-                          &ctx->va_context);
-    if (vas != VA_STATUS_SUCCESS) {
-        av_log(avctx, AV_LOG_ERROR, "Failed to create decode "
-               "context: %d (%s).\n", vas, vaErrorStr(vas));
-        err = AVERROR(EIO);
-        goto fail;
-    }
+    if (ctx->va_context == VA_INVALID_ID) {
+        vas = vaCreateContext(ctx->hwctx->display, ctx->va_config,
+                              avctx->coded_width, avctx->coded_height,
+                              VA_PROGRESSIVE,
+                              ctx->hwfc->surface_ids,
+                              ctx->hwfc->nb_surfaces,
+                              &ctx->va_context);
+        if (vas != VA_STATUS_SUCCESS) {
+            av_log(avctx, AV_LOG_ERROR, "Failed to create decode "
+                   "context: %d (%s).\n", vas, vaErrorStr(vas));
+            err = AVERROR(EIO);
+            goto fail;
+        }
 
-    av_log(avctx, AV_LOG_DEBUG, "Decode context initialised: "
-           "%#x/%#x.\n", ctx->va_config, ctx->va_context);
+        av_log(avctx, AV_LOG_DEBUG, "Decode context initialised: "
+               "%#x/%#x.\n", ctx->va_config, ctx->va_context);
+    }
 #if FF_API_STRUCT_VAAPI_CONTEXT
     }
 #endif
-- 
2.7.4