[FFmpeg-devel] [PATCH v4]avocdec/nvenc: Reconfigure bitrate on the fly

[pkv.stream]

Hi,
in previous versions ReconfigureEncoder was called at each frame once 
bitrate was changed.
Fixed that.
The patch was rebased against 
https://github.com/BtbN/FFmpeg/commit/4e8265e3a63a71a40730e8eb575d8aa760bdcddc
Sorry about the back and forth.
Regards
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From 7c9653faabfe5a9413b2fdcdb7e218991c25ef46 Mon Sep 17 00:00:00 2001
From: pkviet <pkv.stream at gmail.com>
Date: Thu, 3 May 2018 02:15:52 +0200
Subject: [PATCH] avcodec/nvenc: Change bitrate on the fly

The patch enables dynamic bitrate through ReconfigureEncoder method
from nvenc API.
This is useful for live streaming in case of network congestion.

Signed-off-by: pkviet <pkv.stream at gmail.com>
---
 libavcodec/nvenc.c | 38 ++++++++++++++++++++++++++++----------
 libavcodec/nvenc.h |  1 +
 2 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index 3313c376fe..c19b600c4c 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -457,6 +457,8 @@ static av_cold int nvenc_check_device(AVCodecContext *avctx, int idx)
     if ((ret = nvenc_check_capabilities(avctx)) < 0)
         goto fail3;
 
+    ctx->dynamic_bitrate = nvenc_check_cap(avctx, NV_ENC_CAPS_SUPPORT_DYN_BITRATE_CHANGE);
+
     av_log(avctx, loglevel, "supports NVENC\n");
 
     dl_fn->nvenc_device_count++;
@@ -550,6 +552,8 @@ static av_cold int nvenc_setup_device(AVCodecContext *avctx)
             av_log(avctx, AV_LOG_FATAL, "Provided device doesn't support required NVENC features\n");
             return ret;
         }
+        ctx->dynamic_bitrate = nvenc_check_cap(avctx, NV_ENC_CAPS_SUPPORT_DYN_BITRATE_CHANGE);
+
     } else {
         int i, nb_devices = 0;
 
@@ -1935,36 +1939,50 @@ static int reconfig_encoder(AVCodecContext *avctx, const AVFrame *frame)
     NVENCSTATUS ret;
 
     NV_ENC_RECONFIGURE_PARAMS params = { 0 };
-    int needs_reconfig = 0;
-    int needs_encode_config = 0;
     int dw, dh;
+    int reconfig_dar, reconfig_bitrate;
 
     params.version = NV_ENC_RECONFIGURE_PARAMS_VER;
     params.reInitEncodeParams = ctx->init_encode_params;
 
     compute_dar(avctx, &dw, &dh);
-    if (dw != ctx->init_encode_params.darWidth || dh != ctx->init_encode_params.darHeight) {
+    reconfig_dar = dw != ctx->init_encode_params.darWidth || dh != ctx->init_encode_params.darHeight;
+    if (reconfig_dar) {
         av_log(avctx, AV_LOG_VERBOSE,
                "aspect ratio change (DAR): %d:%d -> %d:%d\n",
                ctx->init_encode_params.darWidth,
                ctx->init_encode_params.darHeight, dw, dh);
-
         params.reInitEncodeParams.darHeight = dh;
         params.reInitEncodeParams.darWidth = dw;
-
-        needs_reconfig = 1;
+    }
+    reconfig_bitrate = ctx->dynamic_bitrate > 0 && ctx->rc != NV_ENC_PARAMS_RC_CONSTQP
+        && ctx->encode_config.rcParams.averageBitRate != avctx->bit_rate;
+    if (reconfig_bitrate) {
+        params.version = NV_ENC_RECONFIGURE_PARAMS_VER;
+        params.resetEncoder = 1;
+        params.forceIDR = 1;
+        params.reInitEncodeParams = ctx->init_encode_params;
+        params.reInitEncodeParams.encodeConfig->rcParams.averageBitRate = avctx->bit_rate;
     }
 
-    if (!needs_encode_config)
+    if (!reconfig_bitrate)
         params.reInitEncodeParams.encodeConfig = NULL;
 
-    if (needs_reconfig) {
+    if (reconfig_dar || reconfig_bitrate) {
         ret = p_nvenc->nvEncReconfigureEncoder(ctx->nvencoder, &params);
         if (ret != NV_ENC_SUCCESS) {
             nvenc_print_error(avctx, ret, "failed to reconfigure nvenc");
         } else {
-            ctx->init_encode_params.darHeight = dh;
-            ctx->init_encode_params.darWidth = dw;
+            if (reconfig_dar) {
+                ctx->init_encode_params.darHeight = dh;
+                ctx->init_encode_params.darWidth = dw;
+                av_log(avctx, AV_LOG_VERBOSE, "dar reconfigured\n");
+            }
+            if (reconfig_bitrate) {
+                ctx->encode_config.rcParams.averageBitRate = avctx->bit_rate;
+                av_log(avctx, AV_LOG_VERBOSE, "bitrate reconfigured\n");
+            }
+
         }
     }
 
diff --git a/libavcodec/nvenc.h b/libavcodec/nvenc.h
index c7506d6a15..fd2350aaa6 100644
--- a/libavcodec/nvenc.h
+++ b/libavcodec/nvenc.h
@@ -184,6 +184,7 @@ typedef struct NvencContext
     int weighted_pred;
     int coder;
     int b_ref_mode;
+    int dynamic_bitrate;
 } NvencContext;
 
 int ff_nvenc_encode_init(AVCodecContext *avctx);
-- 
2.16.2.windows.1