[FFmpeg-devel] [PATCH] nvenc: support dynamic aspect ratio change

[Miroslav Slugeň]

If there is input like DVB-T streams it can change aspect ratio 
on-the-fly, so nvenc should respect this change and change aspect ratio 
in encoder.

--
Miroslav Slugeň










>From d836780d56fb7d7a63d91a2af87a0f84743d95d6 Mon Sep 17 00:00:00 2001
From: Miroslav Slugen <thunde...@email.cz>
Date: Sun, 12 Feb 2017 19:51:57 +0100
Subject: [PATCH 1/1] nvenc: support dynamic aspect ratio change

---
 libavcodec/nvenc.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
index 7005465..dea9a1c 100644
--- a/libavcodec/nvenc.c
+++ b/libavcodec/nvenc.c
@@ -913,6 +913,20 @@ static av_cold int nvenc_setup_codec_config(AVCodecContext *avctx)
     return 0;
 }
 
+static void compute_dar(AVCodecContext *avctx, int *dw, int *dh) {
+    int sw, sh;
+
+    sw = avctx->width;
+    sh = avctx->height;
+
+    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
+        sw*= avctx->sample_aspect_ratio.num;
+        sh*= avctx->sample_aspect_ratio.den;
+    }
+
+    av_reduce(dw, dh, sw, sh, 1024 * 1024);
+}
+
 static av_cold int nvenc_setup_encoder(AVCodecContext *avctx)
 {
     NvencContext *ctx = avctx->priv_data;
@@ -949,13 +963,7 @@ static av_cold int nvenc_setup_encoder(AVCodecContext *avctx)
 
     ctx->encode_config.version = NV_ENC_CONFIG_VER;
 
-    dw = avctx->width;
-    dh = avctx->height;
-    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
-        dw*= avctx->sample_aspect_ratio.num;
-        dh*= avctx->sample_aspect_ratio.den;
-    }
-    av_reduce(&dw, &dh, dw, dh, 1024 * 1024);
+    compute_dar(avctx, &dw, &dh);
     ctx->init_encode_params.darHeight = dh;
     ctx->init_encode_params.darWidth = dw;
 
@@ -1644,6 +1652,39 @@ static int output_ready(AVCodecContext *avctx, int flush)
     return (nb_ready > 0) && (nb_ready + nb_pending >= ctx->async_depth);
 }
 
+static int reconfig_encoder(AVCodecContext *avctx, const AVFrame *frame)
+{
+    NV_ENC_RECONFIGURE_PARAMS params = { 0 };
+    NvencContext *ctx = avctx->priv_data;
+    NV_ENCODE_API_FUNCTION_LIST *p_nvenc = &ctx->nvenc_dload_funcs.nvenc_funcs;
+    NVENCSTATUS ret;
+    int dw, dh;
+
+    compute_dar(avctx, &dw, &dh);
+    if (dw != ctx->init_encode_params.darWidth ||
+        dh != ctx->init_encode_params.darHeight) {
+        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.version = NV_ENC_RECONFIGURE_PARAMS_VER;
+        params.reInitEncodeParams = ctx->init_encode_params;
+        params.reInitEncodeParams.darHeight = dh;
+        params.reInitEncodeParams.darWidth = dw;
+
+        ret = p_nvenc->nvEncReconfigureEncoder(ctx->nvencoder, &params);
+        if (ret != NV_ENC_SUCCESS) {
+            nvenc_print_error(avctx, ret, "Failed to reconfigure nvenc on aspect ratio change");
+        } else {
+            ctx->init_encode_params.darHeight = dh;
+            ctx->init_encode_params.darWidth = dw;
+        }
+    }
+
+    return 0;
+}
+
 int ff_nvenc_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                           const AVFrame *frame, int *got_packet)
 {
@@ -1659,6 +1700,8 @@ int ff_nvenc_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     pic_params.version = NV_ENC_PIC_PARAMS_VER;
 
     if (frame) {
+        reconfig_encoder(avctx, frame);
+
         inSurf = get_free_frame(ctx);
         if (!inSurf) {
             av_log(avctx, AV_LOG_ERROR, "No free surfaces\n");
-- 
2.1.4

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