[FFmpeg-cvslog] lavc/videotoolboxenc: fix enabling low-latency encode

[xufuji456]

ffmpeg | branch: master | xufuji456 <839789740 at qq.com> | Wed Jun 21 17:38:33 2023 +0800| [5930d397ef1555d8aba2d1e3d1dc694922650101] | committer: Rick Kern

lavc/videotoolboxenc: fix enabling low-latency encode

Use CFDictionarySetValue to enable low-latency encoding mode.
Since the key is a type of "EncoderSpecification", instead of
"CompressionProperty".

Signed-off-by: xufuji456 <839789740 at qq.com>
Signed-off-by: Rick Kern <kernrj at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5930d397ef1555d8aba2d1e3d1dc694922650101
---

 libavcodec/videotoolboxenc.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/libavcodec/videotoolboxenc.c b/libavcodec/videotoolboxenc.c
index a313087876..6114351392 100644
--- a/libavcodec/videotoolboxenc.c
+++ b/libavcodec/videotoolboxenc.c
@@ -1536,17 +1536,6 @@ static int vtenc_create_encoder(AVCodecContext   *avctx,
         }
     }
 
-    // low-latency mode: eliminate frame reordering, follow a one-in-one-out encoding mode
-    if ((avctx->flags & AV_CODEC_FLAG_LOW_DELAY) && avctx->codec_id == AV_CODEC_ID_H264) {
-        status = VTSessionSetProperty(vtctx->session,
-                                      compat_keys.kVTVideoEncoderSpecification_EnableLowLatencyRateControl,
-                                      kCFBooleanTrue);
-
-        if (status) {
-            av_log(avctx, AV_LOG_ERROR, "Error setting low latency property: %d\n", status);
-        }
-    }
-
     if ((avctx->flags & AV_CODEC_FLAG_CLOSED_GOP) != 0) {
         set_encoder_property_or_log(avctx,
                                     compat_keys.kVTCompressionPropertyKey_AllowOpenGOP,
@@ -1690,6 +1679,13 @@ static int vtenc_configure_encoder(AVCodecContext *avctx)
     }
 #endif
 
+    // low-latency mode: eliminate frame reordering, follow a one-in-one-out encoding mode
+    if ((avctx->flags & AV_CODEC_FLAG_LOW_DELAY) && avctx->codec_id == AV_CODEC_ID_H264) {
+        CFDictionarySetValue(enc_info,
+                             compat_keys.kVTVideoEncoderSpecification_EnableLowLatencyRateControl,
+                             kCFBooleanTrue);
+    }
+
     if (avctx->pix_fmt != AV_PIX_FMT_VIDEOTOOLBOX) {
         status = create_cv_pixel_buffer_info(avctx, &pixel_buffer_info);
         if (status)