h264: add STAP-A (#584)

.github/workflows/mingw.yml

@@ -73,5 +73,5 @@ jobs:
         secret: ${{ secrets.GITHUB_TOKEN }}
 
     - name: "run retest.exe"
-      run: mv retest-exe/retest.exe retest/ && cd retest && ./retest.exe
+      run: mv retest-exe/retest.exe retest/ && cd retest && ./retest.exe -v
       shell: bash

include/re_h264.h

@@ -43,6 +43,8 @@ struct h264_nal_header {
 
 int h264_nal_header_encode(struct mbuf *mb, const struct h264_nal_header *hdr);
 int h264_nal_header_decode(struct h264_nal_header *hdr, struct mbuf *mb);
+void h264_nal_header_decode_buf(struct h264_nal_header *hdr,
+				const uint8_t *buf);
 const char *h264_nal_unit_name(enum h264_nalu nal_type);
 
 
@@ -99,3 +101,6 @@ int h264_nal_send(bool first, bool last,
 		  const uint8_t *buf, size_t size, size_t maxsz,
 		  h264_packet_h *pkth, void *arg);
 bool h264_is_keyframe(int type);
+int  h264_stap_encode(struct mbuf *mb, const uint8_t *frame,
+		      size_t frame_sz);
+int  h264_stap_decode_annexb(struct mbuf *mb_frame, struct mbuf *mb_pkt);

src/h264/nal.c

@@ -6,9 +6,40 @@
 
 #include <re_types.h>
 #include <re_mbuf.h>
+#include <re_net.h>
+#include <re_fmt.h>
 #include <re_h264.h>
 
 
+enum {
+	H264_HEADER_LENGTH   = 1,
+	H264_STAP_MIN_LENGTH = sizeof(uint16_t)
+};
+
+
+static int nal_header_encode_val(struct mbuf *mb,
+				 uint8_t nri, enum h264_nalu type)
+{
+	uint8_t v = nri<<5 | type;
+
+	return mbuf_write_u8(mb, v);
+}
+
+
+void h264_nal_header_decode_buf(struct h264_nal_header *hdr,
+				const uint8_t *buf)
+{
+	if (!hdr || !buf)
+		return;
+
+	uint8_t v = buf[0];
+
+	hdr->f    = v>>7 & 0x1;
+	hdr->nri  = v>>5 & 0x3;
+	hdr->type = v    & 0x1f;
+}
+
+
 /**
  * Encode H.264 NAL header
  *
@@ -257,3 +288,111 @@ bool h264_is_keyframe(int type)
 {
 	return type == H264_NALU_IDR_SLICE;
 }
+
+
+/**
+ * Encode STAP-A header and payload
+ *
+ * @param mb       Target mbuffer for STAP-A NAL unit
+ * @param frame    Input frame in Annex-B format
+ * @param frame_sz Number of bytes in input frame
+ *
+ * @return 0 if success, otherwise errorcode
+ *
+ * NOTE: The value of NRI MUST be the maximum of all the
+ *       NAL units carried in the aggregation packet.
+ *
+ * NOTE: The input must be in Annex-B format (3-4 byte Startcode)
+ */
+int h264_stap_encode(struct mbuf *mb, const uint8_t *frame,
+		     size_t frame_sz)
+{
+	uint8_t nri_max = 0;
+
+	if (!mb || !frame || !frame_sz)
+		return EINVAL;
+
+	size_t start = mb->pos;
+	const uint8_t *end = frame + frame_sz;
+
+	int err = nal_header_encode_val(mb, 0, H264_NALU_STAP_A);
+	if (err)
+		return err;
+
+	const uint8_t *r = h264_find_startcode(frame, end);
+
+	while (r < end) {
+
+		struct h264_nal_header hdr;
+
+		while (!*(r++))
+			;
+
+		const uint8_t *r1 = h264_find_startcode(r, end);
+		size_t len = r1 - r;
+
+		if (len > UINT16_MAX)
+			return ERANGE;
+
+		err  = mbuf_write_u16(mb, htons((uint16_t)len));
+		err |= mbuf_write_mem(mb, r, len);
+		if (err)
+			return err;
+
+		h264_nal_header_decode_buf(&hdr, r);
+		nri_max = max(hdr.nri, nri_max);
+
+		r = r1;
+	}
+
+	/* update NAL header */
+	mb->buf[start] |= nri_max<<5;
+
+	return 0;
+}
+
+
+/**
+ * Decode STAP-A payload and convert to Annex-B NAL units
+ *
+ * @param mb_frame Target mbuffer for frame with multiple NAL units
+ * @param mb_pkt   Input packet with STAP-A payload
+ *
+ * @return 0 if success, otherwise errorcode
+ *
+ * NOTE: The NAL header must be decoded outside
+ */
+int h264_stap_decode_annexb(struct mbuf *mb_frame, struct mbuf *mb_pkt)
+{
+	if (!mb_frame || !mb_pkt)
+		return EINVAL;
+
+	while (mbuf_get_left(mb_pkt) >= H264_STAP_MIN_LENGTH) {
+
+		uint16_t len = ntohs(mbuf_read_u16(mb_pkt));
+
+		if (len < H264_HEADER_LENGTH || len > mbuf_get_left(mb_pkt))
+			return EBADMSG;
+
+#if 0
+		struct h264_nal_header hdr;
+
+		h264_nal_header_decode_buf(&hdr, mbuf_buf(mb_pkt));
+
+		re_printf("STAP-A decode:  len=%u  nri=%u  type=%u(%s)\n",
+			  len,
+			  hdr.nri, hdr.type, h264_nal_unit_name(hdr.type));
+#endif
+
+		static const uint8_t sc3[] = {0, 0, 1};
+
+		int err = mbuf_write_mem(mb_frame, sc3, sizeof(sc3));
+		err |= mbuf_write_mem(mb_frame, mbuf_buf(mb_pkt), len);
+		if (err)
+			return err;
+
+		mbuf_advance(mb_pkt, len);
+	}
+
+	return 0;
+}