[FFmpeg-devel] [PATCH v2] hw_base_enc: inject side data to crop output for AV1

[Lynne]

Unlike H264/H265, AV1 contains no fields to crop encoded output
to specific sizes.
AMD's hardware cannot handle encoding of unaligned dimensions for
AV1, hence it codes 1920x1080 as 1920x1088.

Add side data to crop the output back to the original dimensions.
There's an AV1-spec extension planned to fix this here:
https://github.com/AOMediaCodec/av1-spec/pull/346

But it seems to have stuck for now.
---
 libavcodec/hw_base_encode.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/libavcodec/hw_base_encode.c b/libavcodec/hw_base_encode.c
index 7b6ec97d3b..c28f1aa91c 100644
--- a/libavcodec/hw_base_encode.c
+++ b/libavcodec/hw_base_encode.c
@@ -22,6 +22,7 @@
 #include "libavutil/log.h"
 #include "libavutil/mem.h"
 #include "libavutil/pixdesc.h"
+#include "libavutil/intreadwrite.h"
 
 #include "encode.h"
 #include "avcodec.h"
@@ -551,6 +552,30 @@ int ff_hw_base_encode_set_output_property(FFHWBaseEncodeContext *ctx,
                                 (3 * ctx->output_delay + ctx->async_depth)];
     }
 
+    if ((avctx->codec_id == AV_CODEC_ID_AV1) &&
+        ((avctx->coded_width != avctx->width) ||
+         (avctx->coded_height != avctx->height))) {
+        int err;
+        size_t crop_data_size = 4*4;
+
+        uint8_t *crop_data = av_mallocz(crop_data_size);
+        if (!crop_data) {
+            av_buffer_unref(&pkt->buf);
+            return AVERROR(ENOMEM);
+        }
+
+        AV_WL32(&crop_data[2], ctx->surface_width - avctx->width);
+        AV_WL32(&crop_data[3], ctx->surface_height - avctx->height);
+
+        err = av_packet_add_side_data(pkt, AV_PKT_DATA_FRAME_CROPPING,
+                                      crop_data, crop_data_size);
+        if (err < 0) {
+            av_buffer_unref(&pkt->buf);
+            av_free(crop_data);
+            return err;
+        }
+    }
+
     return 0;
 }
 
-- 
2.45.2.753.g447d99e1c3b