From 9eddaeee3dae1380d661683b2f46cacbedd82e6a Mon Sep 17 00:00:00 2001
From: Michael Jumper <mike.jumper@guac-dev.org>
Date: Fri, 11 Mar 2016 12:31:39 -0800
Subject: [PATCH] GUAC-236: Allocate and maintain frame data for encoding.

---
 src/guacenc/video.c | 49 +++++++++++++++++++++++++++++++++++++++++----
 src/guacenc/video.h |  6 ++++++
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/src/guacenc/video.c b/src/guacenc/video.c
index f4fd1fcd..d0915af9 100644
--- a/src/guacenc/video.c
+++ b/src/guacenc/video.c
@@ -26,6 +26,8 @@
 #include "video.h"
 
 #include <libavcodec/avcodec.h>
+#include <libavutil/common.h>
+#include <libavutil/imgutils.h>
 #include <guacamole/client.h>
 #include <guacamole/timestamp.h>
 
@@ -64,19 +66,35 @@ guacenc_video* guacenc_video_alloc(const char* path, const char* codec_name,
     /* Open codec for use */
     if (avcodec_open2(context, codec, NULL) < 0) {
         guacenc_log(GUAC_LOG_ERROR, "Failed to open codec \"%s\".", codec_name);
-        avcodec_free_context(&context);
-        return NULL;
+        goto fail_context;
+    }
+
+    /* Allocate corresponding frame */
+    AVFrame* frame = av_frame_alloc();
+    if (frame == NULL) {
+        goto fail_context;
+    }
+
+    /* Copy necessary data for frame from context */
+    frame->format = context->pix_fmt;
+    frame->width = context->width;
+    frame->height = context->height;
+
+    /* Allocate actual backing data for frame */
+    if (av_image_alloc(frame->data, frame->linesize, frame->width,
+                frame->height, frame->format, 32) < 0) {
+        goto fail_frame;
     }
 
     /* Allocate video structure */
     guacenc_video* video = malloc(sizeof(guacenc_video));
     if (video == NULL) {
-        avcodec_free_context(&context);
-        return NULL;
+        goto fail_frame_data;
     }
 
     /* Init properties of video */
     video->context = context;
+    video->frame = frame;
     video->width = width;
     video->height = height;
     video->frame_duration = 1000 / framerate;
@@ -89,6 +107,17 @@ guacenc_video* guacenc_video_alloc(const char* path, const char* codec_name,
 
     return video;
 
+    /* Free all allocated data in case of failure */
+fail_frame_data:
+    av_freep(&frame->data[0]);
+
+fail_frame:
+    av_frame_free(&frame);
+
+fail_context:
+    avcodec_free_context(&context);
+    return NULL;
+
 }
 
 /**
@@ -109,6 +138,14 @@ static int guacenc_video_flush_frame(guacenc_video* video) {
     if (buffer == NULL)
         return 0;
 
+    /* Init video packet */
+    AVPacket packet;
+    av_init_packet(&packet);
+
+    /* Request that encoder allocate data for packet */
+    packet.data = NULL;
+    packet.size = 0;
+
     /* STUB: Write frame to video */
     guacenc_log(GUAC_LOG_DEBUG, "Writing frame @ %" PRId64 "ms",
             video->current_time);
@@ -160,6 +197,10 @@ int guacenc_video_free(guacenc_video* video) {
     /* Write final frame */
     guacenc_video_flush_frame(video);
 
+    /* Free frame encoding data */
+    av_freep(&video->frame->data[0]);
+    av_frame_free(&video->frame);
+
     /* Clean up encoding context */
     avcodec_close(video->context);
     avcodec_free_context(&(video->context));
diff --git a/src/guacenc/video.h b/src/guacenc/video.h
index 21787bbc..23879186 100644
--- a/src/guacenc/video.h
+++ b/src/guacenc/video.h
@@ -42,6 +42,12 @@ typedef struct guacenc_video {
      */
     AVCodecContext* context;
 
+    /**
+     * An image data area, containing YCbCr image data in the format required
+     * by avcodec_encode_video2(), for use and re-use as frames are rendered.
+     */
+    AVFrame* frame;
+
     /**
      * The width of the video, in pixels.
      */