[FFmpeg-devel] [PATCH] libavcodec/libx264: add user data unregistered SEI encoding

[Brad Hards]

MISB ST 0604 and ST 2101 require user data unregistered SEI messages
(precision timestamps and sensor identifiers) to be included. That
currently isn't supported for libx264. This patch adds support
for user data unregistered SEI messages in accordance with ISO/IEC
14496-10:2020(E) section D.1.7 (syntax) and D.2.7 (semantics).

This code is based on a similar change for libx265 (commit
1f58503013720700a5adfd72c708e6275aefc165).
---
 libavcodec/libx264.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/libavcodec/libx264.c b/libavcodec/libx264.c
index 9afaf19547..e9bbe8d494 100644
--- a/libavcodec/libx264.c
+++ b/libavcodec/libx264.c
@@ -32,6 +32,7 @@
 #include "internal.h"
 #include "packet_internal.h"
 #include "atsc_a53.h"
+#include "sei.h"
 
 #if defined(_MSC_VER)
 #define X264_API_IMPORTS 1
@@ -114,6 +115,9 @@ typedef struct X264Context {
      * encounter a frame with ROI side data.
      */
     int roi_warned;
+
+    void *sei_data;
+    int sei_data_size;
 } X264Context;
 
 static void X264_log(void *p, int level, const char *fmt, va_list args)
@@ -317,6 +321,9 @@ static int X264_frame(AVCodecContext *ctx, AVPacket *pkt, const AVFrame *frame,
     x4->pic.img.i_plane = avfmt2_num_planes(ctx->pix_fmt);
 
     if (frame) {
+        x264_sei_t *sei = &x4->pic.extra_sei;
+        sei->num_payloads = 0;
+
         for (i = 0; i < x4->pic.img.i_plane; i++) {
             x4->pic.img.plane[i]    = frame->data[i];
             x4->pic.img.i_stride[i] = frame->linesize[i];
@@ -439,6 +446,27 @@ static int X264_frame(AVCodecContext *ctx, AVPacket *pkt, const AVFrame *frame,
                 }
             }
         }
+
+        for (int j = 0; j < frame->nb_side_data; j++) {
+            AVFrameSideData *side_data = frame->side_data[j];
+            void *tmp;
+            x264_sei_payload_t *sei_payload;
+            if (side_data->type != AV_FRAME_DATA_SEI_UNREGISTERED)
+                continue;
+            tmp = av_fast_realloc(x4->sei_data, &x4->sei_data_size, (sei->num_payloads + 1) * sizeof(*sei_payload));
+            if (!tmp) {
+                av_freep(&x4->pic.extra_sei.payloads);
+                av_freep(&x4->pic.prop.quant_offsets);
+                return AVERROR(ENOMEM);
+            }
+            x4->sei_data = tmp;
+            sei->payloads = x4->sei_data;
+            sei_payload = &sei->payloads[sei->num_payloads];
+            sei_payload->payload = side_data->data;
+            sei_payload->payload_size = side_data->size;
+            sei_payload->payload_type = SEI_TYPE_USER_DATA_UNREGISTERED;
+            sei->num_payloads++;
+        }
     }
 
     do {
@@ -505,6 +533,8 @@ static av_cold int X264_close(AVCodecContext *avctx)
     x264_param_cleanup(&x4->params);
 #endif
 
+    av_freep(&x4->sei_data);
+
     if (x4->enc) {
         x264_encoder_close(x4->enc);
         x4->enc = NULL;
-- 
2.27.0