avcodec/libx264: Avoid copying data, allow user-supplied buffers

Here the packet size is known before allocating the packet because
the encoder provides said information (and works with internal buffers
itself), so one can use this information to avoid the implicit use of
another intermediate buffer for the packet data; and by switching to
ff_get_encode_buffer() one can also allow user-supplied buffers.

Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/libx264.c

@@ -28,6 +28,7 @@
 #include "libavutil/time.h"
 #include "libavutil/intreadwrite.h"
 #include "avcodec.h"
+#include "encode.h"
 #include "internal.h"
 #include "packet_internal.h"
 #include "atsc_a53.h"
@@ -144,7 +145,7 @@ static int encode_nals(AVCodecContext *ctx, AVPacket *pkt,
     for (i = 0; i < nnal; i++)
         size += nals[i].i_payload;
 
-    if ((ret = ff_alloc_packet2(ctx, pkt, size, 0)) < 0)
+    if ((ret = ff_get_encode_buffer(ctx, pkt, size, 0)) < 0)
         return ret;
 
     p = pkt->data;
@@ -1147,12 +1148,13 @@ AVCodec ff_libx264_encoder = {
     .long_name        = NULL_IF_CONFIG_SMALL("libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
     .type             = AVMEDIA_TYPE_VIDEO,
     .id               = AV_CODEC_ID_H264,
+    .capabilities     = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
+                        AV_CODEC_CAP_OTHER_THREADS |
+                        AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_data_size   = sizeof(X264Context),
     .init             = X264_init,
     .encode2          = X264_frame,
     .close            = X264_close,
-    .capabilities     = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_OTHER_THREADS |
-                        AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_class       = &x264_class,
     .defaults         = x264_defaults,
 #if X264_BUILD < 153
@@ -1182,12 +1184,13 @@ const AVCodec ff_libx264rgb_encoder = {
     .long_name      = NULL_IF_CONFIG_SMALL("libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 RGB"),
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_H264,
+    .capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
+                      AV_CODEC_CAP_OTHER_THREADS |
+                      AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_data_size = sizeof(X264Context),
     .init           = X264_init,
     .encode2        = X264_frame,
     .close          = X264_close,
-    .capabilities   = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_OTHER_THREADS |
-                      AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_class     = &rgbclass,
     .defaults       = x264_defaults,
     .pix_fmts       = pix_fmts_8bit_rgb,
@@ -1213,12 +1216,13 @@ const AVCodec ff_libx262_encoder = {
     .long_name        = NULL_IF_CONFIG_SMALL("libx262 MPEG2VIDEO"),
     .type             = AVMEDIA_TYPE_VIDEO,
     .id               = AV_CODEC_ID_MPEG2VIDEO,
+    .capabilities     = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
+                        AV_CODEC_CAP_OTHER_THREADS |
+                        AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_data_size   = sizeof(X264Context),
     .init             = X264_init,
     .encode2          = X264_frame,
     .close            = X264_close,
-    .capabilities     = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_OTHER_THREADS |
-                        AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
     .priv_class       = &X262_class,
     .defaults         = x264_defaults,
     .pix_fmts         = pix_fmts_8bit,