$ grep -r ff_h2645_split_packet *
libavcodec/hevc_parser.c:    ret = ff_h2645_split_packet(&ctx->pkt, buf, buf_size, avctx, 0, 0,

$ git blame libavcodec/hevc_parser.c | grep ff_h2645_split_packet
438ed974 (Derek Buitenhuis    2016-04-26 14:07:03 +0100  92)     ret = ff_h2645_split_packet(&ctx->pkt, buf, buf_size, avctx, 0, 0,