[FFmpeg-devel] [PATCH 1/2] lavu/hwcontext_vaapi: cope with race map for YUV420P

[Linjie Fu]

There is a race condition for AV_PIX_FMT_YUV420P when mapping from pix_fmt
to fourcc, both VA_FOURCC_I420 and VA_FOURCC_YV12 could be found by pix_fmt.

Currently, vaapi_get_image_format will go through the query results of
pix_fmt and returned the first matched result according to the declared
order in driver.This may leads to a wrong image_format.

Modify to find image_format via fourcc.

Fix vaapi CSC to I420:
ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -f rawvideo
-pix_fmt nv12 -s:v 1280x720 -i NV12.yuv -vf
'format=nv12,hwupload,scale_vaapi=format=yuv420p,hwdownload,format=yuv420p'
-f rawvideo -vsync passthrough -vframes 10 -y aa.yuv

Reviewed-by: Zhong Li <zhong.li at intel.com>
Signed-off-by: Linjie Fu <linjie.fu at intel.com>
---
 libavutil/hwcontext_vaapi.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
index cf11764..64f14de 100644
--- a/libavutil/hwcontext_vaapi.c
+++ b/libavutil/hwcontext_vaapi.c
@@ -63,6 +63,7 @@ typedef struct VAAPIDevicePriv {
 typedef struct VAAPISurfaceFormat {
     enum AVPixelFormat pix_fmt;
     VAImageFormat image_format;
+    unsigned int fourcc;
 } VAAPISurfaceFormat;
 
 typedef struct VAAPIDeviceContext {
@@ -171,15 +172,21 @@ static int vaapi_get_image_format(AVHWDeviceContext *hwdev,
                                   VAImageFormat **image_format)
 {
     VAAPIDeviceContext *ctx = hwdev->internal->priv;
+    VAAPIFormatDescriptor *desc;
     int i;
 
+    desc = vaapi_format_from_pix_fmt(pix_fmt);
+    if (!desc || !image_format)
+        goto fail;
+
     for (i = 0; i < ctx->nb_formats; i++) {
-        if (ctx->formats[i].pix_fmt == pix_fmt) {
-            if (image_format)
-                *image_format = &ctx->formats[i].image_format;
+        if (ctx->formats[i].fourcc == desc->fourcc) {
+            *image_format = &ctx->formats[i].image_format;
             return 0;
         }
     }
+
+fail:
     return AVERROR(EINVAL);
 }
 
@@ -368,6 +375,7 @@ static int vaapi_device_init(AVHWDeviceContext *hwdev)
             av_log(hwdev, AV_LOG_DEBUG, "Format %#x -> %s.\n",
                    fourcc, av_get_pix_fmt_name(pix_fmt));
             ctx->formats[ctx->nb_formats].pix_fmt      = pix_fmt;
+            ctx->formats[ctx->nb_formats].fourcc       = fourcc;
             ctx->formats[ctx->nb_formats].image_format = image_list[i];
             ++ctx->nb_formats;
         }
-- 
2.7.4