lavc/vaapi_encode: add support for maxframesize

Add support for max frame size:
    - max_frame_size (bytes) to indicate the max allowed size for frame.

Control each encoded frame size into target limitation size by adjusting
whole frame's average QP value. The driver will use multi passes to
adjust average QP setp by step to achieve the target, and the result
may not strictly guaranteed. Frame size may exceed target alone with
using the maximum average QP value. The failure always happens on the
intra(especially the first intra frame of a new GOP) frames or set
max_frame_size with a very small number.

example cmdline:
    ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -f rawvideo \
        -v verbose -s:v 352x288 -i ./input.yuv -vf format=nv12,hwupload \
        -c:v h264_vaapi -profile:v main -g 30 -rc_mode VBR -b:v 500k   \
        -bf 3 -max_frame_size 40000 -vframes 100 -y ./max_frame_size.h264

Max frame size was enabled since VA-API version (0, 33, 0), but query
is available since (1, 5, 0). It will be passed as a parameter in picParam
and should be set for each frame.

Signed-off-by: Linjie Fu <linjie.fu@intel.com>
Signed-off-by: Fei Wang <fei.w.wang@intel.com>

libavcodec/vaapi_encode.c

@@ -365,6 +365,17 @@ static int vaapi_encode_issue(AVCodecContext *avctx,
             goto fail;
     }
 
+#if VA_CHECK_VERSION(1, 5, 0)
+    if (ctx->max_frame_size) {
+        err = vaapi_encode_make_misc_param_buffer(avctx, pic,
+                                                  VAEncMiscParameterTypeMaxFrameSize,
+                                                  &ctx->mfs_params,
+                                                  sizeof(ctx->mfs_params));
+        if (err < 0)
+            goto fail;
+    }
+#endif
+
     if (pic->type == PICTURE_TYPE_IDR) {
         if (ctx->va_packed_headers & VA_ENC_PACKED_HEADER_SEQUENCE &&
             ctx->codec->write_sequence_header) {
@@ -1869,6 +1880,63 @@ rc_mode_found:
     return 0;
 }
 
+static av_cold int vaapi_encode_init_max_frame_size(AVCodecContext *avctx)
+{
+#if VA_CHECK_VERSION(1, 5, 0)
+    VAAPIEncodeContext  *ctx = avctx->priv_data;
+    VAConfigAttrib      attr = { VAConfigAttribMaxFrameSize };
+    VAStatus vas;
+
+    if (ctx->va_rc_mode == VA_RC_CQP) {
+        ctx->max_frame_size = 0;
+        av_log(avctx, AV_LOG_ERROR, "Max frame size is invalid in CQP rate "
+               "control mode.\n");
+        return AVERROR(EINVAL);
+    }
+
+    vas = vaGetConfigAttributes(ctx->hwctx->display,
+                                ctx->va_profile,
+                                ctx->va_entrypoint,
+                                &attr, 1);
+    if (vas != VA_STATUS_SUCCESS) {
+        ctx->max_frame_size = 0;
+        av_log(avctx, AV_LOG_ERROR, "Failed to query max frame size "
+               "config attribute: %d (%s).\n", vas, vaErrorStr(vas));
+        return AVERROR_EXTERNAL;
+    }
+
+    if (attr.value == VA_ATTRIB_NOT_SUPPORTED) {
+        ctx->max_frame_size = 0;
+        av_log(avctx, AV_LOG_ERROR, "Max frame size attribute "
+               "is not supported.\n");
+        return AVERROR(EINVAL);
+    } else {
+        VAConfigAttribValMaxFrameSize attr_mfs;
+        attr_mfs.value = attr.value;
+        // Prefer to use VAEncMiscParameterTypeMaxFrameSize for max frame size.
+        if (!attr_mfs.bits.max_frame_size && attr_mfs.bits.multiple_pass) {
+            ctx->max_frame_size = 0;
+            av_log(avctx, AV_LOG_ERROR, "Driver only supports multiple pass "
+                   "max frame size which has not been implemented in FFmpeg.\n");
+            return AVERROR(EINVAL);
+        }
+
+        ctx->mfs_params = (VAEncMiscParameterBufferMaxFrameSize){
+            .max_frame_size = ctx->max_frame_size * 8,
+        };
+
+        av_log(avctx, AV_LOG_VERBOSE, "Set max frame size: %d bytes.\n",
+               ctx->max_frame_size);
+    }
+#else
+    av_log(avctx, AV_LOG_ERROR, "The max frame size option is not supported with "
+           "this VAAPI version.\n");
+    return AVERROR(EINVAL);
+#endif
+
+    return 0;
+}
+
 static av_cold int vaapi_encode_init_gop_structure(AVCodecContext *avctx)
 {
     VAAPIEncodeContext *ctx = avctx->priv_data;
@@ -2548,6 +2616,12 @@ av_cold int ff_vaapi_encode_init(AVCodecContext *avctx)
             goto fail;
     }
 
+    if (ctx->max_frame_size) {
+        err = vaapi_encode_init_max_frame_size(avctx);
+        if (err < 0)
+            goto fail;
+    }
+
     vas = vaCreateConfig(ctx->hwctx->display,
                          ctx->va_profile, ctx->va_entrypoint,
                          ctx->config_attributes, ctx->nb_config_attributes,

libavcodec/vaapi_encode.h

@@ -191,6 +191,9 @@ typedef struct VAAPIEncodeContext {
     // Desired B frame reference depth.
     int             desired_b_depth;
 
+    // Max Frame Size
+    int             max_frame_size;
+
     // Explicitly set RC mode (otherwise attempt to pick from
     // available modes).
     int             explicit_rc_mode;
@@ -268,6 +271,7 @@ typedef struct VAAPIEncodeContext {
     VAEncMiscParameterRateControl rc_params;
     VAEncMiscParameterHRD        hrd_params;
     VAEncMiscParameterFrameRate   fr_params;
+    VAEncMiscParameterBufferMaxFrameSize mfs_params;
 #if VA_CHECK_VERSION(0, 36, 0)
     VAEncMiscParameterBufferQualityLevel quality_params;
 #endif
@@ -478,7 +482,11 @@ int ff_vaapi_encode_close(AVCodecContext *avctx);
       "Increase this to improve single channel performance. This option " \
       "doesn't work if driver doesn't implement vaSyncBuffer function.", \
       OFFSET(common.async_depth), AV_OPT_TYPE_INT, \
-      { .i64 = 2 }, 1, MAX_ASYNC_DEPTH, FLAGS }
+      { .i64 = 2 }, 1, MAX_ASYNC_DEPTH, FLAGS }, \
+    { "max_frame_size", \
+      "Maximum frame size (in bytes)",\
+      OFFSET(common.max_frame_size), AV_OPT_TYPE_INT, \
+      { .i64 = 0 }, 0, INT_MAX, FLAGS }
 
 #define VAAPI_ENCODE_RC_MODE(name, desc) \
     { #name, desc, 0, AV_OPT_TYPE_CONST, { .i64 = RC_MODE_ ## name }, \