vpxenc: support scaling prior to encoding

Scales the input of the encoder using libyuv's "box filter". Each stream
may have a different width and height specified. If the width (or
height) parameter is missing (or is explicitly set to 0) then the value
will be calculated based on the specified height (or width) and the
input file's dimensions, preserving its aspect ratio. Leaving the height
unspecified behaves similarly.

Change-Id: Ic7026810b13be030826be80dc6f7fc4aaf0c35d0

1 files changed, 36 insertions, 5 deletions

diff --git a/vpxenc.c b/vpxenc.c
index 2f3b6356d..7597e3cbb 100644
--- a/vpxenc.c
+++ b/vpxenc.c
@@ -47,6 +47,7 @@
 #include "y4minput.h"
 #include "libmkv/EbmlWriter.h"
 #include "libmkv/EbmlIDs.h"
+#include "third_party/libyuv/include/libyuv/scale.h"
 
 /* Need special handling of these functions on Windows */
 #if defined(_MSC_VER)
@@ -1642,6 +1643,7 @@ struct stream_state {
   uint64_t                  cx_time;
   size_t                    nbytes;
   stats_io_t                stats;
+  struct vpx_image         *img;
   vpx_codec_ctx_t           decoder;
   vpx_ref_frame_t           ref_enc;
   vpx_ref_frame_t           ref_dec;
@@ -2061,11 +2063,15 @@ static void validate_stream_config(struct stream_state *stream) {
 static void set_stream_dimensions(struct stream_state *stream,
                                   unsigned int w,
                                   unsigned int h) {
-  if ((stream->config.cfg.g_w && stream->config.cfg.g_w != w)
-      || (stream->config.cfg.g_h && stream->config.cfg.g_h != h))
-    fatal("Stream %d: Resizing not yet supported", stream->index);
-  stream->config.cfg.g_w = w;
-  stream->config.cfg.g_h = h;
+  if (!stream->config.cfg.g_w) {
+    if (!stream->config.cfg.g_h)
+      stream->config.cfg.g_w = w;
+    else
+      stream->config.cfg.g_w = w * stream->config.cfg.g_h / h;
+  }
+  if (!stream->config.cfg.g_h) {
+    stream->config.cfg.g_h = h * stream->config.cfg.g_w / w;
+  }
 }
 
 
@@ -2258,6 +2264,28 @@ static void encode_frame(struct stream_state  *stream,
   next_frame_start = (cfg->g_timebase.den * (int64_t)(frames_in)
                       * global->framerate.den)
                      / cfg->g_timebase.num / global->framerate.num;
+
+  /* Scale if necessary */
+  if (img && (img->d_w != cfg->g_w || img->d_h != cfg->g_h)) {
+    if (!stream->img)
+      stream->img = vpx_img_alloc(NULL, VPX_IMG_FMT_I420,
+                                  cfg->g_w, cfg->g_h, 16);
+    I420Scale(img->planes[VPX_PLANE_Y], img->stride[VPX_PLANE_Y],
+              img->planes[VPX_PLANE_U], img->stride[VPX_PLANE_U],
+              img->planes[VPX_PLANE_V], img->stride[VPX_PLANE_V],
+              img->d_w, img->d_h,
+              stream->img->planes[VPX_PLANE_Y],
+              stream->img->stride[VPX_PLANE_Y],
+              stream->img->planes[VPX_PLANE_U],
+              stream->img->stride[VPX_PLANE_U],
+              stream->img->planes[VPX_PLANE_V],
+              stream->img->stride[VPX_PLANE_V],
+              stream->img->d_w, stream->img->d_h,
+              kFilterBox);
+
+    img = stream->img;
+  }
+
   vpx_usec_timer_start(&timer);
   vpx_codec_encode(&stream->encoder, img, frame_start,
                    (unsigned long)(next_frame_start - frame_start),
@@ -2518,6 +2546,9 @@ int main(int argc, const char **argv_) {
     });
 
     /* Update stream configurations from the input file's parameters */
+    if (!input.w || !input.h)
+      fatal("Specify stream dimensions with --width (-w) "
+            " and --height (-h)");
     FOREACH_STREAM(set_stream_dimensions(stream, input.w, input.h));
     FOREACH_STREAM(validate_stream_config(stream));